Can You swim in Days Gone? The answer is No.
You may from time to time land in water with your bike or simply try to swim through a lake and will notice a blue bar that’s slowly depleting. You can stay above water for only a few seconds and if you don’t get back to shore in time will drown. Unfortunately, Deacon (the main protagonist of Days Gone) is unable to swim and this doesn’t change throughout the story. At the end of the game he’ll still be unable to swim.
There are actually a few Nero Research Sites hidden on islands. These can be reached by making long jumps with your motorcycle across ramps while using Nitro. There are however a few places that are unreachable because they are blocked off by water. Driving through water also damages your bike.