Late February, 2019. A small fishing boat carrying six men is caught in a storm off the coast of Brazil and starts going down.Land is visible. Close enough to swim to. Under any normal circumstances, six men would be in the water within seconds.Instead, the crew splits in half. Four of them dive in and start swimming toward the shore. The other two stay aboard the sinking boat and choose to die there, on their own terms.They knew which island that was.About 33 km off the coast of Brazil, near the state of São Paulo, sits Ilha da Queimada Grande. The world knows it as Snake Island, and it is so dangerous that access is strictly forbidden. No tourists. No residents. Nobody at all.The island covers just 430,000 square meters, a speck of land in the Atlantic. Yet some estimates suggest that in certain areas, there is roughly one snake for every square meter of ground. In total, around 4,000 snakes live there, and most of them are golden lancehead vipers, among the most venomous serpents on Earth.Locals refuse to go near it. Stories still circulate about people who landed there and never came back.So what happened to the four men who swam ashore? How deadly is a golden lancehead bite? And why does this island also attract pirates?Nobody has any reason to set foot on Snake Island unless they are maintaining that lonely lighthouse. But if fate dumps you there anyway, here is how you survive.Step 1. Sail carefullyThe best survival strategy is never arriving. If you are sailing or fishing anywhere near the island, keep your distance. Snake Island is ringed by rocks that will wreck your boat and make swimming near the shore dangerous on its own.Which brings us back to those four fishermen.They made it to land, and then they made the single smartest decision of their lives: they refused to go any further. For three days, they stayed exactly where they were, on the open beach, never once stepping into the forest where the vipers live.They drank rainwater. They ate bananas found at the very edge of the treeline. And they waited.On the third day, a boat passed near the island. The four men swam for it, were pulled aboard, and were delivered to the nearest emergency room on the coast.Four survived because they never entered the trees. Two never had to find out what was in them.Step 2. Watch out for cockroachesThe vipers get the headlines, but they are not the only residents. The island also swarms with nonvenomous snakes, locusts, and giant cockroaches crawling through the undergrowth.Check yourself and your surroundings constantly, and avoid them where you can.Then again, if your stomach is strong and you are starving, those cockroaches become dinner. They are safe to eat and packed with protein and essential amino acids. Bon appetit.Step 3. Deal with the snakesSooner or later, you will meet one. Find a stick. It gives you a way to fend the snakes off and keep them from reaching you.If one does bite you, brace yourself, because this venom is unlike anything on the mainland.Isolated on this island, the golden lancehead evolved venom up to five times more powerful than that of a regular lancehead viper. It attacks the body from multiple directions at once, causing kidney failure, brain hemorrhaging, and intestinal bleeding.It also kills muscle tissue, which produces one of the most disturbing sensations a human can experience. Victims describe it as feeling like their skin is melting off.Practical advice in that moment: strip off every ring, watch, and bracelet immediately, because once the swelling starts they become nearly impossible to remove. If you carry an EpiPen, use it for symptoms of anaphylaxis such as swelling of the face, mouth, or throat, hives, or trouble breathing.But none of that saves you. Only one thing improves your odds, and it leads directly to the next step.Step 4. Bring a doctorThe only people permitted on the island are biologists and researchers studying the golden lanceheads, plus the Brazilian navy, which visits once a year to service the lighthouse. That lighthouse has run automatically since the 1920s, so nobody has to live beside the snakes anymore.And the government attaches one non negotiable condition to every visiting team: a doctor must come along.The reason is simple arithmetic. A golden lancehead bite carries roughly a 7 percent chance of killing you. With proper medical treatment on hand, that number drops to about 3 percent.On this island, a doctor is not a precaution. A doctor is the difference.Step 5. Beware of piratesHere is the twist nobody expects. Despite everything you have just read, people deliberately sail to Snake Island on purpose, and not for science.Wildlife smugglers, known as biopirates, land there to trap the vipers and sell them, because a single golden lancehead fetches somewhere between $10,000 and $30,000 on illegal markets.That trade is pushing the species toward the edge. This island is the only place on the planet where golden lanceheads exist, and they are now listed as endangered on the Red List of the International Union for Conservation of Nature.So congratulations. You escaped Snake Island alive, which is more than two fishermen in 2019 were willing to gamble on.Just remember that South America has more than one place like this.