15 Mammals That Mastered the Ocean—and 5 More That Thrive in Both Worlds
They weren’t built for the sea—so they rewrote the rules. Some of the greatest ocean dwellers on Earth didn’t start out as swimmers. These are land-born mammals that dove headfirst into saltwater life and never looked back. They breathe air. They give birth like land animals. But make no mistake—they rule the waves. And a …