It's tough to work out on a 90-degree day. But if you have a nice big pool and an energetic friend, you can get plenty of exercise. Our new Northern fur seal pup, Leu, and Sierra the California sea lion show you how it's done. Watch them porpoise, tumble in the water, chase each other and generally have a great time.



Come to the New Balance Foundation Marine Mammal Center to meet Leu and watch him frolic with his friends. And check out more of Leu's antics here, here and here.