How do true seals swim through water?

True seals, which belong to the family Phocidae, are highly adapted for life in the water. When swimming, a true seal uses its forelimbs to maneuver and steer, while it generates forward propulsion through side-to-side strokes of its hind limbs, a motion similar to that of a fish tail.12

This method of swimming distinguishes true seals from eared seals (such as sea lions and fur seals), which primarily use their long front flippers to propel themselves through the water in a rowing motion. Because true seals have short front flippers and hind flippers that cannot rotate forward under their bodies, they are less mobile on land and must move by wriggling on their bellies.12