Cadborosaurus: Serpent of the Salish Sea

Something in the Whale

It’s 1937. A whaling station in Naden Harbour, British Columbia.

A crew is processing a sperm whale. Routine work. Brutal, smelly, exhausting. Then somebody cuts open the stomach. Inside, they find something that has no business being there.

It’s about ten feet long. It has a small, horse-like head. A long, flexible neck. Flippers. A serrated tail. It doesn’t match any fish they know. It doesn’t match any whale. It doesn’t match anything they’ve pulled out of the sea before.

They photograph it. They show it around. And scientists get involved. Then, somehow, the specimen disappears. Leaving nothing behind, just the photographs.

Those photographs are still being argued about today.

Welcome to Cadborosaurus. Sea monster. Pacific Northwest legend. And possibly, just possibly, something real.

Cadborosaurus at a Glance

Cadborosaurus willsi “The Sea Serpent of the Salish Sea” — Paul LeBlond & Edward Bousfield, Cadborosaurus: Survivor from the Deep (1995)

Characteristics	Description
Type	Sea serpent / cryptid
Length	20–70 feet (6–21 m); Naden Harbour specimen est. 10 feet as possible juvenile
Build	Long, serpentine; large central body with visible humps or coils above waterline
Skin	Reportedly smooth; coloration described variously as dark brown, greenish-black, or grey
Head	Small; horse-like or camel-like; long narrow face
Neck	Long, flexible, clearly distinct from body
Appendages	Flipper-like forelimbs; tail described as serrated or fan-shaped
Movement	Vertical undulation — mammalian, not fish-like
Est. Lung Capacity	500–1,000 liters (mammalian hypothesis); 200–400 liters (reptilian hypothesis)
Est. Breath-Hold	30–90 minutes (mammalian); 20–40 minutes active / up to 7 hours resting (reptilian)
Thermoregulation	Blubber insulation if mammalian; gigantothermy if reptilian — either viable in 8–10°C Salish Sea depth temperatures
Range	Salish Sea; Puget Sound, Strait of Juan de Fuca, Strait of Georgia; sightings from Victoria BC south through the San Juan Islands and into Puget Sound proper
Status	Unverified; proposed as valid species by LeBlond & Bousfield (1995)
Etymology	From Cadboro Bay, Victoria BC, site of early modern sightings; -saurus from Greek sauros, lizard or reptile

Name and Origins

The name comes from Cadboro Bay, near Victoria, British Columbia. That’s where modern sightings started stacking up in the early twentieth century. Local journalists ran with it, and the name stuck.

But “Caddy,” as it came to be known, isn’t just a tabloid invention. Nope, it got a serious scientific treatment.

In 1995, marine biologist Dr. Paul LeBlond and researcher Edward Bousfield published Cadborosaurus: Survivor from the Deep. This was like serious science going on for a sea monster. They reviewed over 200 reported sightings. They analyzed the Naden Harbour photographs. And they proposed a formal scientific name: Cadborosaurus willsi.

That’s a big deal. You don’t get a Latin binomial without someone making a real argument that you exist.

LeBlond and Bousfield weren’t fringe figures chasing headlines either. They were making the case that something large, unclassified, and long-necked was living in the coastal waters of the Pacific Northwest. The scientific establishment mostly pushed back … but they couldn’t entirely dismiss the evidence either.

Indigenous Roots

Here’s the thing about Caddy. The sightings started much earlier. Before European settlers got to Vancouver Island. It didn’t start in 1933 when a Victoria couple spotted something strange in the harbor.

It started much, much earlier.

Coast Salish, Haida, Nuu-chah-nulth, and other Pacific Northwest peoples depicted serpentine sea creatures in their art and oral traditions long before European contact. These weren’t vague sea-monster shapes. They were specific. Long neck. Small head. Large body. Flippers. You get the idea. The descriptions are consistent across nations that had no reason to coordinate their stories.

The Haida called a similar creature Hiitl’iit. The Manhousat people of Vancouver Island had their own name and their own stories. These weren’t cautionary tales designed to keep children away from the water, like folktales. They were descriptions of something people encountered.

When European settlers started reporting Caddy in the twentieth century, Indigenous people along the coast were not surprised. They had known about this animal for generations.

Let’s sit with that a moment … centuries of consistent, independent description from people who spent their lives on this water. People who didn’t know each other and rarely contacted each other. That’s critter corroboration and that’s not nothing.

What Does Caddy Look Like?

Across hundreds of reported sightings, the description is remarkably consistent, which indicates legend drift hasn’t happened. It’s a strong indication that witnesses have corroborated the claims. Folks, this is not common in the monster world. Just look at Batsquatch.

Back to the description …

The head is small. Witnesses compare it to a horse, a camel, or a giraffe — something with a long, narrow face. The neck is long and flexible. The body is large, with a series of humps or coils visible above the waterline. There are flippers, or flipper-like appendages. The tail is described as serrated or fan-shaped.

The whole animal runs somewhere between twenty and seventy feet long, depending on the account. (Note: Most people overestimate the size of objects in water by 30%–50%)

Here’s the detail that marine biologists find most interesting: Caddy moves with a vertical undulation. Up and down, like a dolphin or a whale. Not side to side, like a fish or a snake.

That’s a mammal or reptile movement. Not a fish movement.

Whatever Caddy is, it’s not a very large fish.

Habitat: The Salish Sea as a Monster’s Home

The Salish Sea comprises Puget Sound, Strait of Juan de Fuca and Strait of Georgia in the Pacific Northwest

Let’s talk about where Caddy supposedly lives. Because the Salish Sea is a remarkable place.

The Salish Sea is the collective name for the connected inland waters of the Pacific Northwest: Puget Sound, the Strait of Juan de Fuca, and the Strait of Georgia. Together they form one of the largest and deepest inland sea systems in North America.

And deep is the key word.

Hood Canal, the long fjord-like arm of Puget Sound, drops to over 600 feet. The Main Basin of Puget Sound reaches nearly 900 feet in places. The water is surprisingly warm for its latitude. It averages 46°F to 50°F at 100-ft. deep, and it’s stable all year. Perfect conditions for a large sea creature.

But the visibility drops fast. Below a certain depth, it is genuinely dark and largely unexplored. This isn’t the Caribbean. You can’t see the bottom from the surface. You can’t see much of anything.

A large animal could live in these waters and surface rarely enough that sightings would be occasional and hard to verify. The Salish Sea has complex underwater topography — deep trenches, underwater ridges, submerged channels — that would give a reclusive animal plenty of places to go.

Sightings cluster around the areas you’d expect if Caddy were using the deep basins as refugia and coming up to shallower water to feed. The San Juan Islands. Admiralty Inlet, where the Strait of Juan de Fuca meets Puget Sound. The waters around Victoria and Vancouver Island. The northern Sound.

These aren’t random. They’re the places where deep water meets productive, fish-rich shallows. Which brings us to what Caddy would be eating.

Diet and Feeding

A forty-foot animal needs a lot of calories. Let’s think about what the Salish Sea could offer.

The answer is … a lot.

The Salish Sea supports massive runs of Pacific salmon — Chinook, coho, sockeye, pink, and chum. It has huge populations of Pacific herring, which form dense schools near the surface. There are squid. There are rockfish. There are harbor seals and Steller sea lions, both of which would be viable prey for a large predator.

The ecosystem is rich. It’s one of the most productive marine environments on the West Coast.

A long-necked predator hunting in the Salish Sea would likely hunt from below. Come up under a school of herring or salmon. Strike fast from the depth. The long neck would be useful for this — it could extend quickly to snatch prey before the school scattered.

There’s also a darker contemporary angle here. Puget Sound Chinook salmon are in serious decline. They’re listed as threatened under the Endangered Species Act. If Caddy is real and salmon are a significant part of its diet, the collapse of the runs isn’t just bad news for orcas. It could be putting pressure on every large predator in the Sound, including ones we haven’t officially discovered yet.

Speculative Natural History: A Survivor

This is the section where things get genuinely interesting.

If Caddy is real, what is it? Where did it come from? How has it survived?

There are three main hypotheses, and each one is worth considering seriously.

The Plesiosaur Hypothesis

This is the crowd favorite. Plesiosaurs were marine reptiles that lived alongside the dinosaurs. They had exactly the body plan people describe when they describe Caddy: small head, long neck, large body, four flippers.

The problem is the fossil record. Plesiosaurs disappear from it 66 million years ago, at the same extinction event that wiped out the non-avian dinosaurs. That’s a long gap. A very long gap.

There’s also a practical problem. Plesiosaurs were reptiles. They had to breathe air. A population of them living in the Salish Sea would need to surface regularly. We would have better evidence by now.

Most scientists reject the plesiosaur hypothesis on these grounds. But “most scientists reject it” isn’t the same as “it’s impossible.”

The Zeuglodon Hypothesis

This one is more scientifically plausible and less well known.

Basilosaurus — sometimes called zeuglodon — was an early primitive whale. It lived roughly 40 million years ago. It was enormous. Some species reached sixty feet. And here’s the key part: it didn’t look like a modern whale. It had a long, serpentine body. A relatively small head. Vestigial hind limbs.

In the water, a basilosaurus would have looked a lot like what people describe when they describe Caddy.

The hypothesis is that a lineage of primitive whales survived in the deep, cold waters of the North Pacific — isolated, rarely surfacing in populated areas, slowly evolving in a direction separate from modern whales.

It sounds far-fetched. But the North Pacific is vast and deep. And we have a precedent.

The Coelacanth Precedent

In 1938 — one year after the Naden Harbour carcass — a South African museum curator named Marjorie Courtenay-Latimer pulled a strange fish out of a local fisherman’s catch.

It was a coelacanth. A species scientists had declared extinct for 65 million years. Just swimming around in the Indian Ocean like nothing had happened.

The ocean hides things. It hides them well. It hid an entire species of large, distinctive fish for 65 million years before a museum curator happened to notice one in a fishing haul.

If the ocean can do that with a coelacanth, it can do it with something else.

How Would Caddy Survive to the Modern Day?

If we’re doing speculative natural history, let’s go all the way.

A Caddy population in the Salish Sea would need to be self-sustaining. That means at least dozens of individuals, probably more. They would need to breed. They would need to manage their body temperature in cold-ish Pacific water, which suggests warm-bloodedness, or at least some form of endothermy, similar to modern leatherback sea turtles and some large sharks.

The vertical undulation movement suggests a mammalian or mammal-like physiology. It breathes air, which means it surfaces. But a shy, deep-water animal could surface in open water, at night, far from shore, and be seen rarely. More on this a little later …

Solitary or small groups. Long-lived, like most large marine animals. Slow reproductive rate. Which means a small population would be slow to recover from any significant loss.

It’s a coherent biology. It doesn’t require magic. But I’ve got doubts …

Speculative Biology: How Caddy Would Actually Work

Let’s say Caddy is real. Let’s say it’s a large aquatic mammal — a surviving lineage of primitive whale, something in the basilosaurus family. How would its body actually function in the cold, deep water of the Salish Sea?

Breath-holding

This is one of the most revealing questions you can ask about a mystery animal.

If Caddy is mammalian, the comparison class is deep-diving whales. Sperm whales manage 90 minutes between breaths. Cuvier’s beaked whales — the current world record holders — have been documented holding their breath for over three hours. A large primitive whale in Caddy’s size range could plausibly surface every 30 to 90 minutes.

Think about what that means for the sighting record. An animal that needs air every 45 minutes, moving through a body of water the size of the Salish Sea, surfacing briefly and unpredictably — possibly in open water, possibly at night — would be seen rarely. Maybe a few times a decade by anyone close enough to know what they were looking at.

If Caddy is reptilian, the math changes but the conclusion is similar. Large sea turtles can rest underwater for four to seven hours. An active hunting reptile would need to surface more frequently — perhaps every 20 to 40 minutes. Still plenty of time between appearances.

Either way, Caddy’s breathing schedule alone explains most of the sighting gap.

Lung Capacity

Marine mammals have evolved disproportionately large, highly collapsible lungs. They can compress almost completely at depth without injury, something that would kill a human diver.

A 40-foot mammal in the Caddy size range would likely have lungs in the range of 500 to 1,000 liters. To put that in perspective, that’s roughly the interior volume of a Volkswagen Beetle.

But lung size isn’t the whole story. Marine mammals store oxygen directly in their muscle tissue using a protein called myoglobin. It’s why whale meat is nearly black: Their muscles are saturated with it. Myoglobin lets the animal keep working its muscles long after its lungs are empty. A Caddy-sized mammal would have enormous reserves of it.

A reptilian Caddy would have smaller, less efficient lungs — perhaps 200 to 400 liters — but a much lower metabolic demand. Reptiles burn oxygen slowly. The math is mathing.

Staying Warm

The Salish Sea sits at around 46 to 50 degrees at depth year-round. That’s cold. Cold enough to kill an unprotected human in under an hour. How would Caddy stay active in water like that?

A mammalian Caddy would likely be endothermic — warm-blooded — with a thick layer of blubber for insulation. Modern cetaceans maintain core body temperatures around 98.6°F regardless of water temperature. Their blubber layer can be a foot thick or more. On a 40-foot animal, that’s a significant thermal barrier.

There’s also a more exotic possibility. Leatherback sea turtles are reptiles, technically cold-blooded, and yet they actively hunt in water as cold as 40°F. They manage this through gigantothermy — the sheer mass of their bodies retains heat generated by muscle activity. A very large reptile generates more heat than it loses, simply because of the ratio of volume to surface area. The bigger you are, the easier it is to stay warm.

A 40-foot Caddy, even if fully reptilian, might stay warm through gigantothermy alone. No blubber required. Just mass.

The cold water, in other words, is not the obstacle it might seem. For an animal big enough and built right, the Salish Sea in January is perfectly habitable.

Caddy’s Role in the Ecosystem

Every apex predator shapes its ecosystem. Wolves change how deer move, which changes which trees survive, which changes entire river systems. We call this the trophic cascade.

If Caddy is real, it’s been part of the Salish Sea ecosystem for a long time. Long enough to shape things.

A large, deep-water predator would regulate populations of seals, sea lions, and large fish. It would create what ecologists call a “landscape of fear” — prey animals behaving differently because a predator might be present, even when that predator isn’t visible. This changes feeding patterns, movement patterns, and ultimately the whole structure of the ecosystem.

There’s a concept called the “ghost predator.” It’s a large predator that shapes its environment primarily through fear rather than direct predation. Animals that have evolved alongside a ghost predator behave cautiously in certain habitats, avoid certain depths or areas, cluster differently than they otherwise would.

Has the behavior of Salish Sea marine mammals been partly shaped by something large living in the deep basins? We have no way to know. But it’s not an unreasonable question.

There’s also the human angle. Fishermen around the Salish Sea have reported unexplained net damage for a long time. Large nets fouled or torn in open water, in ways that don’t match known hazards. Unexplained wakes. Things seen and not talked about, because fishermen have practical reputations to protect.

If those reports mean anything, Caddy hasn’t just been watching us. It’s been bumping into us for a long time.

Caddy and Humans: A Long Relationship

The relationship between Caddy and the people of the Salish Sea goes back further than any written record.

Indigenous nations along the coast didn’t just describe Caddy. They built relationships with it. In some traditions, encountering the sea serpent was a significant spiritual event — not necessarily dangerous, but not casual either. It meant something. Fishermen knew which waters were associated with the creature. They adjusted accordingly.

When European settlers arrived and started working the same waters, they brought different frameworks. They didn’t have centuries of knowledge about what lived here. So when they saw something they couldn’t explain, it went into the newspaper.

The modern sighting record kicks off in earnest in the 1930s. A Victoria couple spots something in the harbor in 1933. The newspapers love it. The name “Cadborosaurus” gets coined. And suddenly people who had seen things but stayed quiet start coming forward.

Naval officers. Commercial fishermen. Lighthouse keepers. These are not people prone to hysteria. Their accounts are specific, detailed, and consistent.

The sighting record runs to over 300 reports by most tallies. They span from the waters around Victoria and Vancouver Island down through the San Juan Islands, Admiralty Inlet, and into Puget Sound proper. They span nearly a century of modern documentation, and centuries more of Indigenous testimony before that.

Then came 2009. A video shot in Alaska appeared to show a large, undulating creature moving through open water. It went briefly viral. Biologists looked at it. Nobody could definitively explain it. Nobody could definitively confirm it. It disappeared from the news cycle the way these things do.

Today, with smartphones in every pocket and kayakers on every inch of the Sound, Caddy sightings keep coming. The reports are less dramatic than the old ones, often. A long shape seen at distance. Something large that dove before anyone could get a good look. An unusual wake in calm water.

The Naden Harbour Carcass

Let’s go back to 1937.

The carcass pulled from that sperm whale’s stomach was photographed by multiple witnesses at the Naden Harbour whaling station. The photos show an elongated creature with a distinct head and neck, separated from the body by a clear narrowing. There appear to be flipper-like appendages. The tail end shows what witnesses described as a serrated or fluked structure.

The creature was described as approximately ten feet long, but witnesses believed it may have been a juvenile.

Scientists who have examined the photographs over the decades have proposed various explanations. A fetal baleen whale — these can look strange before full development. A decomposing basking shark, which are notorious for producing “sea monster” carcasses as they decay. An oarfish, which are long, ribbon-shaped, and genuinely strange-looking.

None of these explanations fully satisfy everyone who has looked carefully at the photographs.

A fetal baleen whale doesn’t have the right head shape. A decomposing basking shark doesn’t explain the apparent neck structure. An oarfish doesn’t have flippers.

The most frustrating part of the Naden Harbour story isn’t the photographs. It’s what happened to the specimen.

It was not preserved. It was not sent to a museum. It was apparently discarded. Exactly what happened to it depends on which account you read. By the time anyone with serious scientific credentials was paying attention, there was nothing left to examine.

That’s the short story of Caddy. We came so close to understanding what it could be. And … then it’s gone before we could understand it.

But there’s some hope we could make a discovery …

Modern Technology and the Search for Caddy

Here’s where it gets exciting.

We have tools now that didn’t exist in 1937. Or 1995, when LeBlond and Bousfield published their book. The technology to actually find Caddy — if it’s there — exists right now.

Environmental DNA

This is the big one.

Every animal sheds DNA into its environment constantly. Skin cells. Scales. Waste. Mucus. A large marine animal swimming through the Salish Sea is leaving a trail of genetic material behind it in the water.

Environmental DNA, or eDNA, sampling allows scientists to take a water sample and analyze it for genetic material from any species present. It’s already being used to track rare and endangered marine species. It was used to confirm the presence of great white sharks in certain coastal areas before anyone had spotted one there visually.

If Caddy exists and maintains a breeding population in the Salish Sea, it is shedding DNA into that water right now.

Has anyone done a systematic eDNA survey of Puget Sound and the Strait of Juan de Fuca specifically looking for large unclassified species? Not in any published, peer-reviewed way — at least not yet. It would be expensive. It would require institutional support. But it is entirely feasible.

Hydrophone Arrays

The U.S. Navy has maintained underwater listening arrays in the Pacific Northwest for decades. Originally built to track Soviet submarines, these hydrophone networks can detect sounds from hundreds of miles away.

Marine biologists have since used this infrastructure to track whale calls, monitor seismic activity, and study underwater soundscapes. The famous “Bloop” — an unidentified underwater sound recorded in 1997 — was picked up by this kind of equipment.

A large marine animal produces sound. It moves water. It breathes at the surface. A systematic analysis of existing hydrophone data from the Salish Sea, filtered for biological signatures that don’t match known species, is theoretically possible.

Autonomous Underwater Vehicles

AUVs — underwater drones — can now map the seafloor and water column in detail, operating for extended periods without a crew. The deep basins of Hood Canal and the Main Basin of Puget Sound have been partially mapped, but not exhaustively.

A targeted survey of the areas where sightings cluster, using AUVs equipped with sonar and cameras, could either find evidence of something large living in those basins or narrow the possibilities considerably.

Citizen Science

This one is low-tech but potentially powerful. A coordinated network of Salish Sea users — kayakers, ferry passengers, whale watch operators, commercial fishermen — equipped with a standardized reporting app and GPS logging could build a real sighting database within a few years.

Whale watch companies already informally track unusual sightings. Formalizing that into a structured dataset would be genuinely useful.

The technology to find Caddy exists. The question is whether anyone will point it at the right piece of water.

The Science: Could Caddy Be Real?

Let’s be honest about where the scientific consensus sits.

Most marine biologists are skeptical of Cadborosaurus. A large, unclassified marine animal living in a relatively well-studied body of water like the Salish Sea seems unlikely to have evaded formal documentation this long. The Salish Sea is not the deep ocean. It has ferries crossing it daily. It has research vessels, fishing boats, and recreational traffic year-round.

The counterarguments are real, though.

The deep basins of Puget Sound are not well studied below 200 feet. Novel species are still being discovered in the ocean regularly — including large ones. The giant squid wasn’t photographed alive in its natural habitat until 2004. A species of beaked whale new to science was described as recently as 2016.

The ocean routinely surprises us.

The sighting record for Caddy is unusually consistent for a cryptid. Three hundred-plus reports, spanning nearly a century of modern documentation and centuries of Indigenous testimony before that, describing the same basic animal in the same basic waters. That consistency doesn’t prove anything. But it does demand an explanation.

The most scientifically cautious position isn’t “Caddy definitely exists.” It’s “we haven’t looked carefully enough to rule it out.” Given the tools now available — particularly eDNA sampling — that’s a gap that could be closed.

Cold Water Keeps Its Secrets

The Salish Sea is deep and cold and dark below a certain point.

We know more about some parts of the moon’s surface than we know about the floor of Hood Canal. We have mapped less than twenty percent of the world’s ocean floor in meaningful detail. The ocean is large. It is old. It has been keeping its own counsel for a very long time.

Somewhere in a university freezer or a research vessel’s storage, there may already be water samples from the Salish Sea that contain the answer to Cadborosaurus. Unanalyzed. Waiting.

The 1937 crew at Naden Harbour held something in their hands that could have changed the scientific understanding of this coast. Then it was gone.

We might not get another chance like that. But we have something they didn’t have.

We have the tools to ask the water directly.

The ocean doesn’t owe us an explanation. But it might be leaving us clues.

Bibliography

Bousfield, E.L. and LeBlond, P.H. (1995). Cadborosaurus: Survivor from the Deep. Horsdal & Schubart Publishers.

Carrington, R. (1957). Mermaids and Mastodons. Rinehart.

Costello, P. (1974). In Search of Lake Monsters. Coward, McCann and Geoghegan.

Heuvelmans, B. (1968). In the Wake of the Sea-Serpents. Hill and Wang.

LeBlond, P.H. and Sibert, J. (1973). “Observations of Large Unidentified Marine Animals in British Columbia and Adjacent Waters.” Manuscript Report No. 28, Institute of Oceanography, University of British Columbia.

Moon, M. (1977). Ogopogo: The Okanagan Mystery. Air Publishing.

Naish, D. (2016). Hunting Monsters: Cryptozoology and the Reality Behind the Myths. Arcturus Publishing.

Pyle, R.L., et al. (2003). “A New Species of Mesoplodon (Cetacea: Ziphiidae) from the Tropical Pacific Ocean.” Marine Mammal Science 18(3).

Smith, J.L.B. (1956). Old Fourlegs: The Story of the Coelacanth. Longmans, Green.