Cat5 cable for low voltage underwater application
Nobody will give you any sort of guarantee.
It may or may not work, you have to try this experiment.
It is hard to say that the heat will not build up in the middle of the cable. There is an isolation between water and wires itself. So it will isolate heat transfer from the wires to the water. Yes, cold water will help with cooling. But will it be enough to keep the wires at acceptable temperature? Hard to say. My guess is yes, it will work. But as I said, no guarantee.