None of the filters should be used underwater or during water activity unless specified on the product packing.
As such, ND, ND/PL, and CPL filters have no role in improving your footage underwater, they are to be used on the ground to create motion blur in case of ND, ND/PL & removing reflection for CPL.
Using filters near heavy water activity, such as swimming, water-skiing, etc., or natural storms can build pressure damaging the optics by creating moisture.
