Sea Otters are native to California and I'm told they used to be all up and down the west coast. That said, there seem to be a lot of them in Monterey Bay. Watching Sea Otters is without a doubt one of life's little treats, it's very relaxing. 

Sea Otters are actually an endangered specie so keep your distance. I've found that a pair of binoculars gets you really close and you'll see that they are truly delightful to watch. If you want to get really close go to the Monterey Bay Aquarium, feeding time is always fun to watch. I'd also recommend Moss landing, Monterey harbor, and the board walk areas as places to see otters in a more natural habitat. There are usually rafts of otters all around the bay so you just have to look carefully for them. Please remember they are protected, so look but don't approach or disturb them. All of the pictures are from Moss Landing.