There's several guides and youtube vids that show some of the cool wrecks and stuff under water. You'll definitely want to check them out. Also, the briefcases are strange. Sometimes they appear, sometimes they don't. They do respawn however, but with nowhere near the frequency as they did before the patch. There's a couple of them I've looted multiple times over the last week or so. Here's a map to the package locations, most of them have some cool things nearby: http://i.imgur.com/rvfRxUh.jpg
And here's a map for the sub parts. There's some overlap between the two, but more sights to see. http://i.imgur.com/L6NRKHj.jpg
Hey lady, long time no post. The last two posters were very helpful. Sharks do pop up on the map as a red dot, kinda like cougars. There's a bunch of stuff underwater to explore, sunken ships and planes, beautiful landscapes and such. Can't help you on the suitcases as I haven't searched for any since the last patch.
You can pick up some pretty handy weapons underwater, the rocket launcher pops up done there in a few places and its very helpful early one.
Potential mid game spoilers:
The name of the mission escapes me but there's a mission where you takedown a Merryweather cargo plane. Said plane crashes into the Alamo sea, there isn't much to find so don't expect to. However, there's some weapons down there that could be helpful but that's about it.
I am enjoying the game, regardless of the driving physics. Since we're on the subject I must say, there should've been more "story based" mission involving the underwater areas. The underwater areas are so beautiful but neglected story wise, which a ton of people will never really experience because of lack of story based underwater missions. Kinda a missed opportunity but whatever, I love this game. Hasn't left my system since launch. Well, except for that one time my daughter changed discs to watch a My Little Pony DVD.
Vegetarian- an old Indian word meaning bad hunter Elected Leader of both PS3 and 360 GTAV boards