This video from the USA says about itself:
Owl ‘Swims’ for Its Life in Rare Video | National Geographic
13 June 2017
See rare video of a swimming great horned owl. Hikers walking through a canyon in Lake Powell between Arizona and Utah stumbled upon the rare sight. It’s likely a young great horned owl and still has some of its nestling feathers. Great horned owls often roost on cliff ledges, so it’s possible the young owl fell into the water from its nest. Seeing an owl swim is unusual, and they have no way to defend themselves while in the water. Owls are unable to take flight while swimming, so they must leave the water and dry their feathers before flying.