Leopard seals are true seals, in the family Phoecidae. They move on land like a lumbering caterpillar, their hind flippers are fused to the pelvis in a way that means they cannot bring them together under their bodies to walk on them. This is in contrast to the Otariids, the eared ‘seals’, which are actually sea lions and fur seals; and who can get across land with speed.
But underwater Leopard Seals beat the sea lions "flippers" down. They are extremely streamlined and can swim out far from land to find food, and are adapted to diving to decent depths and can spend a long time underwater between breaths