There is a hatch under the water that shines with a bright light.
Since the game came out very large, this article will probably have a status of 'one hundred percent completed' probably very soon, so you can add it to your bookmarks and check it once a week as it gets filled and new finds. And since the genre of easter eggs itself in games originated a long time ago, a decent amount of secrets has accumulated. Secrets of GTA 5 were no exception, harboring, like the previous parts of the Grand Theft auto, a large number of secret places and surprises from the developers.
