Ilha da Queimada Grande, nicknamed Snake Island, is a 430,000-square-metre (43-hectare) island off the coast of the state of São Paulo, Brazil.^[1][2] It is home to an endemic species of Bothrops, the Golden Lancehead Viper (Bothrops insularis), which is one of the most venomous snakes in the world. Much about its venom is disputed, as no cases of humans having been bit have been confirmed.^[3]

The Golden Lancehead is the only species of snake on the island, and is considered in danger of extinction since it has no other habitat, only feeds on migratory birds, and might be wiped out by a wildfire. The viper population may also be at risk from inbreeding, effects of which are evident in the population. Nevertheless, statistics from 2004 show that the population is stable. A 2015 estimate by a herpetologist on a Discovery Channel documentary states that there are about four thousand Golden Lancehead vipers living on the island.

A Discovery Channel documentary, Treasure Quest: Snake Island, claimed that there is between two and four thousand snakes on the 430,000 square meter island, which equates to an average of one snake per approximately 75 square meters over the entire island. This contrasts with claims of an average of one to as many as five snakes per square meter.^[4]

Plans to build a banana plantation on the island fizzled, but this is likely the origin of the island's name, as in Portuguese, queimadais a name for a slash-and-burn fire (i.e., to clear land for agriculture); so, the island's name would mean "the island of the big land-clearing fire." A lighthouse was constructed on the island in 1909.^[5] For a long time, the island's only inhabitant was a lighthousekeeper, who reportedly ran out of food and went missing trying to gather wild bananas from near the shore. According to legend, he and the members of his rescue party died one by one, all alone and in search of one another after each had been missing for some time. The lighthouse is now automated.^[1][6]

Currently, the Brazilian Navy bans civilians from the island, though scientists sometimes receive waivers.