These sub-adult males are the first to move into new areas. Male rafts are made up of all ages of males in non-breeding season. These animals are much more comfortable in water than on land, and spend most of their time at the surface floating on their backs. Sea otter pups are born in water and float like corks, but they can't swim for several weeks. Perhaps this is why females typically have one pup at a time.
Sea otters have one of the thickest fur coats in the animal kingdom.
Sea otters depend on their fur to keep them warm, as they have no insulating blubber layer. It is critical that sea otters keep their fur clean to maintain an insulating air layer between the water and their skin. At birth, a newborn sea otter's coat, called a lanugo, acts like a life preserver and keeps the baby floating at the water's surface. It takes at least two months before the extra-buoyant lanugo is fully shed. Only then can the pup dive.