The paper k&n's type filters(actually cotton fiber) were originally designed for dirt applications to keep dust out. Then peeps started putting them on watercraft when PWC's first came out.
Yes, the fiber would get wet and it would swell and block off air flow... Its lame..
So peeps would then put nylon "outerwears" on and spray them with silicone spray to repel water off them. It is still lame.
The paper is meant to keep dust out.. no dust inside a ski.
The only kind you want is the wire mesh type. Prok, k&N, FLy, OEM, etc., all make the fine wire mesh type.
Best way to keep water out is a good aftermarket freestyle/freeride hood or modding the OEM like one.