20. Snake Island, Brazil
Ilha da Queimada Grande (a.k.a Snake Island) is a tiny island off the coast of Brazil. Snake Island is home to the venomous golden lancehead snake (Bothrops insularis) which has an incredibly lethal venom known to cause more human mortalities than any other group of snakes in either North or South America. There is estimated to now be between one and five snakes per square meter. Consequently Snake Island is completely off limits to the public.