Stretching for 280 miles, the seven Izu Islands are in Japan’s Fuji Volcanic Belt, and the reek of sulfur cannot be avoided or ignored. Residents were actually evacuated in 2000 for five years because of the gas levels, and the people of the island of Miyakejima must wear masks at all times.

Izu Islands

The Caribbean island of Saba in the Lesser Antilles chain is a special municipality of the Netherlands that is best to visit during the winter. According to the Caribbean Hurricane Network, it has been hit by more major storms from 1851 to 2010 than any other place on Earth, including a total of 64 severe hurricanes.

Saba

About 25 miles west of San Francisco, the Farallon Islands are mostly off-limits to people, other than a few conservation scientists at a field research station. Though the exact location — and impact — is unknown, more than 47,800 drums of low-level radioactive waste were reportedly dumped nearby in the ocean between 1946 and 1970.

Farallon Islands

Located off Africa’s east coast and said to be infected with malaria-carrying mosquitos, few people visit Comoros and most people there wear masks. World Travel Guide says the water should be considered potentially contaminated and needs to be boiled before use, as should milk; Hepatitis E is widespread, and Hepatitis B is hyper-endemic.

Comoros

Reunion Island in the Indian Ocean is home to one of the highest amounts of shark attacks in the world, with more than 12 attacks in just the last three years. The government has put a ban on swimming, body-boarding, and surfing in hopes of protecting beach-goers.

Reunion Island