There's a terrifying place called Snake Island that's home to thousands of the deadliest vipers on Earth

There’s a chunk of land off the coast of Sao Paolo, Brazil that has the highest concentration of venomous snakes in the world.

It’s called Ilha da Queimada Grande, better known as “Snake Island,” and it’s home to 2,000 golden lancehead vipers (Bothrops insularis).

These snakes are among the most venomous in the world. Even if you get a dose of anti venom right after you’re bitten, you’re probably still going to die.

Local fisherman in Sao Paolo tell tales of people who have ventured onto the island in search of food and other resources, and never returned. Some believe that pirates brought the deadly snakes there to protect a trove of golden galleons.

Whether there’s truth to local legend or not, the Brazilian navy closed the island to the public in the 1920s. Now the only time anyone can legally set foot on the island is an annual trek by trained navy personnel to tune up the automated lighthouse on the island, and for research experiments conducted by a handful of specially trained scientists who are studying how the snakes’ venom could be used in biopharmaceuticals.

VICE’s editor-in-chief Rocco Castoro and senior producer Jackson Fager tagged along with the Brazilian navy’s latest trip to the island.

You can watch the full VICE documentary, or tour the island through our slideshow.

Snake Island is home to 2,000 deadly golden lancehead vipers. The island is the only place this particular species exists.

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The island is marked by the red pin here. It's about 100 miles off the coast of Brazil.

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Since this is the only place in the world that the species exists, it's critically endangered. The species came into existence when the island split off from the mainland and the snakes on the island evolved differently than their mainland relatives.

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The Brazilian navy declared the island off limits to the public decades ago. Only navy personnel and a few researchers are allowed on the island now. VICE editor-in-chief Rocco Castoro and senior producer Jackson Fager got special permission to accompany the navy on an annual maintenance trek to the dangerous island. After about eight hours at sea, Snake Island's ominous silhouette appeared in the distance.

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There's only one spot to dock along the island's rocky, inhospitable coastline. It's a slippery patch of algae.

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Visitors to the island have to climb up a steep rocky slope and then plunge into the dense underbrush where the vipers lurk.

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The island is home to an estimated 2,000 snakes. From the moment you step on shore you can expect to see a snake every 10 to 15 minutes. As you walk further into the center of the island, you'll come across a snake every 6 square yards, according to researchers.

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A family used to live on Snake Island during the 1920s. They were in charge of keeping the lighthouse on the island lit to help guide ships sailing to and from South America. But legend has it that not too long after settling on the island, snakes found their way into the family's home one night. Each family member was bitten and died. The rescue workers sent to look for the family met the same fate.

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Now the lighthouse operates automatically, but an annual maintenance trip is required so workers can replace burned out lights and fuses.

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Despite all the precautions the workers take, they can't anticipate everything. A snake appeared inside the lighthouse hiding among the equipment that Castoro was sitting on just moments before.

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There's no official documented case of anyone being bitten by one of these golden lanceheads because no one has ever survived long enough to make it to the hospital.

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But experts say if you're bitten by a snake in this genus, the bite site first swells up and gruesomely blisters. Vomiting, intestinal bleeding, kidney failure, brain hemorrhaging and muscle necrosis may follow.

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Chemical analysis of this specific species' venom suggests it may be five times more toxic than the next-fastest acting venom in the snake's genus.

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The island species may have evolved to have such a potent venom to help them quickly catch and kill birds. The snakes have no natural predators on the island, but there's also no ground-based prey for them to feed on. So instead, the snakes took to the trees and hunt migratory birds that use the island as a pit stop during their long journey.

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The VICE team talked with Marcelo Duarte, the lead researcher at the Butantan Institute, a research company that specialises in developing biopharmaceuticals made from snake venom. Duarte says there's already evidence that golden lancehead viper venom could be used to combat heart disease and improve circulation. 'We're just scratching the surface,' Duarte told VICE.

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That's why a handful of researchers make regular trips out to the island to capture and study the snakes. The VICE reporters tagged along for the catch and release field work.

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The researchers measure and weigh each snake they catch.

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Then they inject it with a tracking device so they can monitor the snakes long-term.

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After measuring and tagging the snakes, the researchers carefully release them.

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But researchers aren't the only ones with a vested interest in the snakes on Snake Island. Wildlife smugglers called 'bio pirates' are illegally catching and selling the snakes. One snake can fetch anywhere between $10,000 and $30,000 on the black market.

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Even though the island is teeming with snakes, the numbers are actually dwindling, probably due in part to bio pirates. Security cameras on the island are set up to try and catch any trespassers.

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It's unclear why buyers are willing to pay so much for the snakes, but a few theories exist. VICE got one of these bio pirates to talk to them about the illegal trade. In the documentary, his face is blacked out and he goes by the alias 'Juan.' Juan said if someone is caught smuggling snakes they go to prison. But most smugglers get out of jail quickly by bribing inspectors. Sometimes even the inspectors are involved in the illegal trade.

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Some people think the buyers who are willing to pay so much for just one snake are trying to beat pharmaceutical companies to a patent on the snakes' venom. The researchers who make trips to the island are often approached by buyers when they return.

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Catching and releasing snakes took most of the day, so the researchers and VICE reporters spent the night on the island.

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They spotted five snakes slithering through the trees by their campsite before bed. Sweet dreams?

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Snakes aren't the only thing visitors to the island have to worry about. Giant cockroaches and locusts swarm over the ground. The researchers and reporters had to carefully clean up camp before going to sleep or they would be knee-deep in cockroaches by morning.

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In the VICE documentary, Castoro said he could feel the roaches crawling around beneath him as he laid down to sleep.

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Castoro says he has no plans to ever go back to the hellish island. 'I couldn't help but think the only reason we survived is because Snake Island let us,' Castoro says at the end of the documentary.

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You've seen Snake Island now deep-dive with an ocean giant.

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