There's something about oceans in videogames that freaks me out.
For example, Subnautica's early game, before you get your submarine and Prawn Suit is just completely terrifying due to how helpless you are. Diving into a cave and seeing a fucking crashfish suddenly come out and start swimming at me made me scream in sheer panic.
And GTAV. The shallow waters are fine and even beautiful to look at, but taking a sub and venturing deeper lets you reach the point where sunlight stops piercing the water and suddenly you're in pitch black. No sunlight, no angler fish, not even your submarine lights work due to having nothing to possibly illuminate and everything is silent save for your engine.
There's no danger unless you go too deep and get yourself crushed, but you do have to go pretty dangerously close to the high pressure to get some of the collectable waste barrels. Even with the lack of threats though, that place just deeply unsettles me.