How Snake Island where no human is allowed to visit became infested with 4,000 of world’s deadliest snakes

The story behind the infamous Snake Island and how so many of the deadliest predators ended up concentrated in the same place has been explained.

Brazil isn't short of tropical locations and islands, but Ilha de Queimada Grande, which is 90 miles off the coast of São Paulo is not one that you'd probably be looking to visit.

Locals know to steer clear of the area, and are likely thankful that the 106-acre island is so far out at sea, where approximately 4,000 highly venomous species of snake wait to feast on visiting animals.

Snake Island is known as one of the most dangerous islands in the world, and is considered too hazardous for humans, with visitation to the island prohibited by the Brazilian government and permission only granted to select researchers and scientists.

The dangerous yet critically endangered venomous golden lancehead inhabit the island, featuring a fatal venom that can kill humans within an hour after entering the bloodstream.

A YouTuber even managed to evade authorities and sneak his way onto the island in 2023, and luckily made it out alive without encountering any of the deadly predators.

He took a long boat ride and ventured to the famous lighthouse on the island, all while wearing some hard metal armour to protect himself from any attacks.

But why is the island so heavily populated with particularly dangerous snakes?

Snake Island is home to thousands of lethal snakes (Getty Stock Photo)

Golden lancehead vipers are one of the deadliest species of snakes in the world, so much so that nobody lives on the island anymore.

From 1909 to the 1920s, people did live there to run its lighthouse, but a tale tells that the last lighthouse keeper and his family were killed when a load of snakes made their way into their house through the windows.

But the reality of it is that Ilha de Queimada Grande's dense population of snakes started about 11,000 years ago, according to Smithsonian Magazine.

When sea levels rose to isolate the island from mainland Brazil, the snakes on the island, believed to be jararaca snakes, evolved differently to their mainland relatives.

This is because snakes left on the island had no ground level predators, so they they could reproduce rapidly, though having no predators meant they also had no ground level prey, so to eat, the snakes slithered upward and preyed on migratory birds that would seasonally visit the island.

Snakes here have evolved to have some of the deadliest venom in the world (9 News)

Usually, snakes stalk and then bite their prey, coming back after their venom had taken effect.

Golden lancehead vipers can't track birds, so their venom evolved to be very potent and efficient, estimated to be three to five times stronger than snakes on the mainland.

It is capable of killing prey almost instantly.

It is estimated that the island is so heavily populated with snakes that there's a snake for every square metre in certain areas, with a bite from a golden lancehead carrying a seven percent chance of death.

If it doesn't do that, it can cause kidney failure, necrosis of muscular tissue, brain hemorrhaging and intestinal bleeding.

So yeah, Snake Island is somewhere to steer clear of then.