No, there is no evidence that polar bears sleep in the water. A sea otter can sleep on water, floating on its back, but a polar bear's body density makes this impossible.
the sea is technically floating on the earth, as at the bottom of the sea there are techtonic plates.. Our oceans are just gigantic canyons that are filled to the brim with water.
Killer Whales sleep by floating on the surface.
I do not know about you, but when I am floating in the sea, I can definitely feel I am floating.
Floating
Floating turtles tend to sleep with their eyes open. This ability to sleep with their eyes open helps them to stay alert and detect potential threats in their environment even while they are resting.
Sea snakes can sleep while floating on the surface of the water. They have a special adaptation that allows them to sleep with half of their brain at a time, keeping the other half awake to monitor their surroundings and prevent themselves from drowning. This phenomenon, known as unihemispheric slow-wave sleep, enables sea snakes to rest and remain alert to potential threats at the same time.
Land floating on the sea
the Sikorsky sea king.
they can sleep in the sea water or they can sleep on land
They don't sleep!
Astronuts have to be tied to their beds at night to stop them from floating!