Myth spoilers alert 
It's weird how many extra missions pop up when you think you're finished - I bought a place in the top left corner of the map and it opened up missions for Michael to do, about searching for 30 submarine parts or something. As it involves a lot of deep swimming I'm paranoid about a shark tearing me apart so I'm not sure if I'll have the bottle to complete it or not. Had a bit of a fear of sharks tearing at me ever since i watched Jaws as a kid...
You must have bought the Sonar place, I'm saving up for that but I'm at the point in the game where you don't really make any money from missions. You don't have to swim for that, you go around the coast in the sub (located at the place you just bought) and just drive over them to collect them and you receive $23,000 each. That why I want it, for the profit! I think someone said you earn about $400,000 when you collect all 30. Only downside is that apparently you have to collect all of the radioactive material in the very slow submarine and there is about a 30 second gap between each and I think it involves driving around the whole of the map and it takes hours!. So if you exit and got back to continue later you have to start from the start again and drive back round to where you got to. I plan to do half then go round the map in the opposite direction when I decide to do the other half. Apparently you can pick the sub up with the cargobob but I think that will take just as long anyway as I don't think you can use the app to locate it in the heli, only the sub. Last thing, you can only collect them once so no unlimited money from it
Also I was referring to the mysterious map drawn on one of the walls at the top gondola station, have a look at it. The other message is on the back of the viewing platform at the top on the mountain, and there is a eye/symbol painted on the floor under it.
It's where you go at 3am in the morning during a rain storm to see the UFO floating in the sky.Ok more info on the easter eggs.
There is a massive search going on to find a jetpack apparently hidden in the game somewhere like a puzzle believed to be linked with all the UFO myths to gain access to a secret room in the army base or hidden tunnels within Mt Chilliad (where the jetpack may be).
I've seen what you get when you collect all 50 of the alien aircraft parts, kinda funny what you get but people think it is part of a key to unlock another easter egg or the jetpack.
2 (or 3?) alien spaceships including the one that you see at the top of Chilliad have been found just floating in the sky about 3/4 up to the game height limit. When you get close to them your engine shuts off, if you fire at them it has a force field, if you're lucky enough to land on it then you land on the force field and go flying off if you get close to the centre of it.
wow, that's enough typing now...
