On holiday in California four years ago we travelled down Highway One along the coast from San Francisco to Los Angeles and saw sea otters off the Pebble Beach 17 mile drive. They were floating on their backs some 15 metres offshore, too far to see if they had kittens with them (are they kittens, pups or cubs?). Whether we were lucky or this was a common sight there I don’t know. Looking up details later I found that the adult male weighs 70 to 90 pounds and is about 4.5 feet long – rather longer than a European river otter (lutra lutra) and at least twice the weight.