a Sea-Troll
Most of the Dark lord's creatures were deadly afraid of the powers of Ulmo and shunned the Element of Water.This was not entirely true for the rare breed of the Sea-Trolls (Or."Dotlog").Bred by Sauron along with the new Olog-hai breed these Creatures might still have suffered from bright daylight, but they were able to move in Water and were even sufficient swimmers.Sea-Trolls steered the Dark Lord's Doom Ships, the great barges of Núrn.