The Bering Sea is a marginal sea of the Northern Pacific Ocean, separated from the Gulf of Alaska by the Aleutian Islands. It is named after Vitus Bering, a Danish navigator in Russian service. During the Ice Ages, sea levels dropped enough to expose a land bridge known as Beringia, which connected Asia to North America and allowed for the migration of humans and animals between the continents. Today, the Bering Sea is one of the world's most productive fishing grounds, particularly for king crab and pollock. However, it is also one of the most dangerous, known for its freezing temperatures, massive waves, and heavy sea ice. The ecosystem is currently experiencing rapid changes due to the loss of Arctic sea ice, which affects the migration patterns of whales, walruses, and polar bears that depend on the ice for survival.