u/Mental-Service-8140

Hi, just want to see if anyone else has the same experience. I mainly shoot underwater when scuba diving, and this time i tried filming a wakeboarding session. However, the footage seems really grainy/noisy(compared to underwater) even when shot in 4K. I'm wondering if it has to do with the distance of the subject from the camera (approx 15m). Is it normal for the quality to drop off alot at that distance? iPhone footage seemed way better...

Setup:
In waterproof dive housing (so I don't have to wash the camera)
4K 60FPS
Rocksteady+, Wide
Auto exposure & WB
Normal 10bit colour

Any advice is greatly appreciated