Not my favourite means of travel, but I seem to spend an inordinate amount of time swimming in the waters off Skellige, these days. 'Why not just take a boat?' you may ask? So far, I've lost one boat inside an island -- slipped through the graphics at the edge of the map -- another by striking a hidden shoal, another by hitting a submerged piece of wreckage, another to Sirens; and I've also managed to strand several more boats on beaches, between rocks, and one or two merely never made it away from dockside (stuck). I've also damaged quite a few vessels just by gently bumping into piers and barrels. In addition, I tend to leave the boats that didn't sink in inconvenient spots. And, finally, disembarking can be rather perilous, as there's often that sudden thousand foot drop from the sky. So, Geralt just swims rather a lot, now.