The document describes the key features of the four major oceans: the Atlantic Ocean formed as the Americas spread away from Europe and Africa, features few trenches and island arcs; the Pacific Ocean is the largest and oldest ocean basin with an asymmetrical shape and features the Ring of Fire of trenches, island arcs, and volcanic ranges; the Indian Ocean is similar to the Atlantic but symmetrical around a triple junction and features trenches and island arcs like Java; the Arctic Ocean is the smallest ocean basin almost entirely landlocked except for its connection to the North Atlantic and contains the continental shelf dividing Lomonosov Ridge.