On South Africa's Wild Coast, divers travel near and far for a chance to take part in the world's largest sardine run.

These cave explorers never know what they will find but they are on a mission to map as many unexplored cave systems as they can.

Scapa Flow in Scotland holds many World War I and World War II shipwrecks for scuba divers to explore.

A team of scuba divers from Russia explores under the ice to find sea angels in the chilly White Sea.

Scuba divers explore a flooded uranium mine shaft in Poland and uncover its dark roots from World War II.

Scuba divers can explore the sunken World War II aircraft off Vis Island in Croatia.

After unleashing the most powerful weapons in history at the end of World War II, the U.S. military needed more data. Today, the Pacific atoll where it tested its doomsday bombs is a Holy Grail for divers.

See why the scuba diving on North America's Pacific coast — from Alaska to Washington to California and Mexico — is among the best in the world.

Scuba divers can explore an abandoned opal mine in Slovakia, one of the most enchanting dive sites in the world.