There is an island about 30 nautical miles offshore of the city of São Paulo, Brazil, known locally as the "Hell's Island" because it is only a highly venomous snake island

On this island there are nearly a thousand of the world's deadliest snakes——— the Golden Gun-headed Cave Snake, which is very aggressive in nature and is known as the most dangerous snake in Brazil
Severe pain, dizziness, nausea, vomiting, sweating, headaches, and eventually intracranial hemorrhage, concomitant renal failure caused by hypotension, and cerebral cortex necrosis can occur when bittenated by this snake
The island is listed as a forbidden island by the local government, and tourists are forbidden to visit the island because few people survive the snake bite