They actually have 4 movement.

I wish you could use a unit in the transport to tport to a part of the ocean that's under your border, though.  I built one on my only beach which I wound up finding out I could not get out of because a part of the waterway out to the main part of the ocean was blocked by another nation's borders. :/  I had a lot of ocean squares in my borders past that, but even with my sov on board, I couldn't tport the boat.

Yes, teleporting the boat would be cool. Also on larger map sizes you get a bonus to moves for transports by default. Even a little research too to increase the number of moves would be nice.