Humans are obsessed with monsters. We want them to be real. There’s something deeply humbling—and honestly, terrifying—about the idea of a 37 ft great white shark patrolling the coastline while we paddle around on surfboards. It taps into that primal fear of the "big one." But if you’ve seen the viral posts or read the old textbooks claiming these thirty-footers exist, I have to break it to you: they're basically a giant game of historical telephone.
The math doesn't work. The biology doesn't work. And the records? They're mostly just old-school typos.
The Port Fairy "Giant" and Where the Legend Began
Let's talk about 1870. That was the year a massive great white shark was reportedly caught in a herring weir at Port Fairy, Victoria, in Australia. This is the "patient zero" of the 37 ft great white shark myth. For over a hundred years, this specific shark was cited in the Guinness Book of World Records and several scientific journals as the largest ever recorded. It was the gold standard for shark enthusiasts.
But there was a problem. A big one.
In the 1970s, a researcher named John Randall decided to actually look at the evidence. Since the shark itself was long gone, he went to the British Museum to examine the only part left behind: the jaws. Here’s the thing about sharks: their teeth grow in a very specific proportion to their body length. Randall measured those Port Fairy teeth and realized something embarrassing for the 19th-century scientific community. Based on the enamel height and the width of the jaw, that shark wasn't 36 or 37 feet long. It was barely 16 feet.
Someone, somewhere, had just written the number down wrong. Or maybe they were eyeballing a wet, heavy carcass on a beach and let their imagination run wild. We've all been there. You catch a trout and it's "this big," but by the time you tell your friends, it’s a whale.
False Alarms and the False Bay Myth
South Africa is famous for its "flying" great whites, but it’s also famous for some pretty tall tales. There was another report of a 37 ft great white shark (sometimes cited as 36.5 feet) caught near False Bay in the 1930s. Similar to the Port Fairy case, this measurement wasn't verified by anyone with a ruler and a PhD. It was anecdotal.
Large sharks look bigger than they are.
When a 2,000-pound animal is thrashing next to a boat, your brain isn't exactly a precision instrument. Most modern shark experts, like those at the Gavin Naylor’s Florida Program for Shark Research, agree that the biological ceiling for a Carcharodon carcharias is likely around 20 to 21 feet.
Anything beyond that? You’re moving out of the realm of biology and into the territory of Megalodon. And even those ancient giants didn't usually reach the lengths people claim for "Deep Blue" or other modern legends.
Why Can't They Get That Big?
Physics.
The square-cube law is a buzzkill. Basically, if you double the length of a shark, you don't just double its weight—you cube it. A 37-foot shark wouldn't just be "longer" than a 20-footer; it would be an absolute mountain of meat. The energy requirements to move that much mass through the water would be astronomical. It would need to eat a small whale every other day just to keep its heart beating.
The Real Giants: Deep Blue and Her Rivals
If we stop chasing the ghost of a 37 ft great white shark, we can actually appreciate the real monsters that do exist. Because, honestly, a 20-foot shark is plenty big enough to ruin your afternoon.
Deep Blue is probably the most famous shark on the planet. She was filmed by Mauricio Hoyos Padilla off Guadalupe Island. She’s estimated to be around 20 feet long and is likely over 50 years old. When you see the footage of her swimming next to divers in a cage, she looks like a padded-out submarine. Her girth is what’s really shocking. She isn't just long; she is wide.
Then there’s "Nukumi," a massive female tagged by OCEARCH in the North Atlantic. She clocked in at 17 feet, 2 inches and weighed over 3,500 pounds. These are the real-world limits of the species.
- Deep Blue: ~20 feet (Guadalupe Island)
- The T-Bolt: ~19 feet (South Australia)
- Haole Girl: ~19 feet (Hawaii)
If a 37 ft great white shark actually existed, it would be nearly double the length of Deep Blue. Imagine two Deep Blues stacked nose-to-tail. That's what we're talking about. It would be visible from space (okay, not really, but you get the point).
The Megalodon Confusion
A lot of the "big shark" sightings people report today are actually just misidentifications of Basking Sharks. Basking sharks are huge—often reaching 30 feet—and they have a dorsal fin that looks remarkably like a Great White's from a distance. They’re filter feeders. They’re basically big, swimming cows that eat plankton. But if you see a 30-foot grey shape in the water and you’re already primed to think about Jaws, your brain fills in the gaps.
Also, we have to blame Discovery Channel a little bit. Their "documentaries" about Megalodon still being alive did a number on public perception. They used "found footage" styles that felt real to a lot of viewers, leading people to believe that a 37 ft great white shark or even a 50-foot Megalodon is just hiding in the Mariana Trench.
Spoiler: It’s not. The Mariana Trench is freezing and has almost no food. A Great White would starve and freeze in about twenty minutes down there.
Is It Technically Possible?
In science, we rarely say "impossible." We say "statistically improbable."
Could there be a freak of nature out there? A shark with a pituitary gland disorder that just never stopped growing? Maybe. But the ocean is heavily monitored. We have satellite tagging, sonar, and thousands of GoPros in the water every single day. We’ve found the Colossal Squid. We’ve found the Oarfish. We haven't found a 37 ft great white shark.
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If such a beast existed, it would leave a massive trail of "predatory events." We’d be finding humpback whales bitten clean in half. We don't find those. We find bite marks from 15 to 18-foot sharks, which are already impressive enough.
How to Spot a Fake Shark Story
The next time you see a headline about a "Megashark" or a 37 ft great white shark spotted on Google Earth, look for these red flags:
- Low Resolution: If we can see the craters on the moon, we can get a clear photo of a shark near the surface. If it’s blurry, it’s probably a rock or a pod of dolphins.
- No Scale: Without a boat or a person in the frame for reference, size is impossible to judge.
- The "Expert" is Anonymous: Real marine biologists from places like Oceana or the Atlantic White Shark Conservancy are usually the first to debunk these things. If the article doesn't cite a specific scientist, it’s probably clickbait.
The reality is that great whites are in trouble. We spend so much time worrying about "monster" sharks that we forget the actual sharks are struggling with overfishing and habitat loss. A 17-foot shark is an apex predator that deserves our respect, not just our fear. We don't need to invent a 37 ft great white shark to make the ocean interesting. It's already plenty wild.
Steps for the Curious Shark Fan
If you want to track the real giants—the ones we actually have proof for—don't look at tabloids.
Check out the OCEARCH Shark Tracker app. It’s free. You can see real-time pings from tagged Great Whites like "Nukumi" or "Breton" as they migrate thousands of miles. It shows you their actual measured length at the time of tagging.
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If you're ever at a beach and think you see a "monster," look at the dorsal fin. If there’s a second fin trailing far behind it, you’re likely looking at a harmless Basking Shark. If you see a single, tall, triangular fin moving with purpose, give it space. It doesn't need to be 37 feet long to be the boss of the water. Respect the 15-footers; they’ve earned it.
Stop looking for the ghost of Port Fairy. The real 20-footers are much more impressive because they actually exist.