Sea urchins, crabs, clams, mussels, octopus, other marine invertebrates, and fishes make up the normal diet of sea otters. They usually dive to the bottom in 5 to 250 feet of water and return with several pieces of food, roll on their backs, place the food on their chests and eat it piece by piece using their forepaws and sometimes a rock to crack shells. In the wild, sea otters never eat on land. The search for food is one of the most important daily activities of sea otters, as large amounts are required to sustain the animal in healthy condition. Feeding dives generally last less than one minute although some otters are capable of staying underwater for five minutes or more.
Captive animals require a daily food intake equal to one-quarter of their body weight.
Their feeling habits may result in conflicts with subsistence, recreational, and commercial fishers when otters move into areas that support important shellfish resources. They are sometimes caught and drowned in fishing nets. The Exxon Valdez oil spill dramatically demonstrated the effects of oil contamination on sea otters. More than 1,000 carcasses were found after the spill, and it is likely that the total number that died was several times greater. Thus, while sea otters are flourishing in Alaska's waters, it is clear that they are susceptible to human activities.