Besides walruses and sea lions, the various types of seals include, of course, common seals. They don't spend much time on land, and usually swim in the icy waters of the North Atlantic and the Arctic Ocean. While hunting for fish and shellfish, common seals dive 200 m deep and can hold their breath for up to 30 minutes.
Common seals and sea lions are easy to tell apart. Sea lions have little ears, while common seals do not.