Alright, we've already found two Ocean Monuments. Doge and Klip found one, while I found the other. The coordinates for the one I found are roughly:
x: 2876 y: 63 z: 559
Really don't recommend anyone going Rambo into it and trying to get all of the loot. Doge and I were getting pushed around by the Guardians in our attempt. We didn't even make it into the actual temple. Granted, we were severely under-equipped. But hey! We managed to take out three Guardians LOL. Also, there is a constant lag in the server right now, and it only gets worse when you go into the ocean.
EDIT: Okay, guys. Lockette is disabled for whatever reason due to the update. So, be careful, I guess.