As you can see, it features a vast ocean dotted with islands and a new swimming mechanic! (kickstarter.com)
There is no half - baked swim mechanic or prone thrown in just to make the game feel varied. (thekoalition.com)
There is also a hint at the possibility of an enhanced underwater swimming mechanic within the game, but for now fans will have to wait and see if this will be a playable feature. (plusxp.com)