Whether it (hardware) will work for you when you want it to (at infrequent intervals) depends on an incredible number of factors. We do it "all-the-time", as pretty much a matter of routine, for many a client. Try your favorite Company providing Commercial Diving Services... For many locations around the globe, look for us at:
... after some more thought I think I now understand what it is you are looking for... a submersible directional control valve solenoid. I have run into the same problem myself, and we ended up making our own pressure housing for a single valve. If you are interested we could get you a quote on that particular assembly.