Generally you should keep your distance from wild animals, especially in the case of marine mammals, as the failure to do so can result in a hefty fine. But there are those rare times when wild animals won't leave you be. In that case, having a camera rolling can make for some amazing scenes, like the above.
Sea lions and seals are pinnipeds, carnivorous mammals with fin-like flippers that come ashore to breed, give birth, and nurse their young. It's a group that also includes walruses and is more closely related to such land animals as bears, dogs, raccoons, and weasels (all belonging to the order Carnivora) than to cetaceans like whales and dolphins, which took the plunge millions of years earlier in evolutionary history.
Like all animals though, sometimes they're just looking for a free ride.