4 Kilauea – Hawaii
Hawaii is well-known for its beautiful beaches, huge waves, and ideal tanning climate, but it is not without risk. Hawaii also contains several volcanoes, the most active of which being Mt. Kilauea. The sand on Kilauea Beach is abnormally black due to volcanic ash, and while it is a beautiful site to visit, there is still a risk of the volcano exploding. It should make you think twice about going here, especially given that it has been in active since 1983.