4. Ilha de Queimada Grande, Brazil
Ilha de Queimada Grande is a small island off the coast of Brazil and is better known as Snake Island. The Brazilian Navy has banned anyone from visiting the island as it is completely covered by venomous snakes.
5. Miyake – jima
Miyake – jima is a small Japanese island where the active volcano Mount Oyama´s recent eruptions lasted for four years (2000-2004). The outbreak from the volcano ejected toxic sulfur vapors. When they reach a certain level, an alarm sounds across the island and all inhabitants will have to put on a gas mask.