I made this forum for everyone interested in the ocean/river/se/lake part of GTA V.
Anyway I've found three different whale skeletons, one at the southern-west area of the map, near shallow water. I found another one near the lighthouse at the upper part of the map in front of the nearest island to the lighthouse. It was also in rather shallow water. I also found a third skeleton which I remember being quite deep in the ocean, sadly i cannot remember the exact location, i believe it was near the sunken nuclear sub, right at the right tip of the map, down at the bottom of the map near the sunken plane or at the other sunken plane near the sonar collections dock.
Also, am I the only one scared/creeped out of the ocean in GTA V, I just find swimming or driving around the bottom of the ocean extremely creepy, I keep thinking some massive or weird looking thing will pop up.