I have a game with a large/seemingly endless ocean, and I don't wanna generate tons of 1k by 1k parts to make the floor, is there a better way to limit how far down you can fall without running through every player and detecting their y-axis position?
There really is no other alternative that is not going to look very buggy/glitch and cause problems with the player trying to move when you set their Torso's CFrame. I'd say limit how for out they can go (e.g. 6k studs or so). They'd probably never want to go out that far anyway, and with StreamingEnabled with the options of setting graphics levels, AND todays modern PC's? It's not really a big deal. That's only 3 of the largest blocks (2048 max stud size I believe) anyways, unless they changed it. You don't really have a choice here, and I don't see why that's a bad thing.