The first tank is a U.S. tank that did not make it in the invasion. We used to swim in the water there, and used the tank as a diving platform. If I remember correctly, there were three or more under the water. The Saipan Blogger said that these tanks are still there today, and that there are a total of three.
The next one, I think, is a Japanese tank.
The third tank, with the star on it is a U.S. Army tank.