This is a harbor seal (Phoca vitulina) who lives at the zoo in Milwaukee with his wife and kid. Many people equate seals and sea lions...related but not the same. You can tell a seal because it propels itself forward with its hind flippers (snake like movement) and uses the front flippers to turn. A sea lion is the opposite using it's front flippers to propel itself and it steers with its hind flippers.
Sea lions are also much larger. Depending on species, male sea lions can reach 11 feet (3.35 m) in length and weigh as much as 2500 pounds (1334 kg).
Harbor seals average 5 feet (1.5 m) in length and weigh about 130 pounds (59 kg)