Meet the Kelpie

Another new beast is the Kelpie, which is a creature that lives underwater and sports camouflage that resembles long, thick strands of green kelp.

The Kelpie is described as "extremely strong and hard to tame, with a nasty bite." However, once bridled, it is docile and, for those who know how to handle it, the Kelpie can provide a fast underwater ride, as seen here with Newt hitching a lift.