The Chukchi Sea Shelf or Chukchi Shelf is the westernmost part of the continental shelf of the United States and the easternmost part of the continental shelf of Russia. Within this shelf, the 50-mile Chukchi Corridor acts as a passageway for one of the largest marine mammal migrations in the world. The Chukchi Shelf is shared between Russia and the United States according to the 1990 USSR–USA Maritime Boundary Agreement.