Ilha da Queimada Grande, is a 430,000-square-metre island off the coast of the state of São Paulo, Brazil. 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. Because of this the island nicknamed Snake Island.
Currently, the Brazilian Navy bans civilians from the island, though scientists sometimes receive waivers.
[Source: Atlas Obscura]