I would add that getting the battery out of the drone as soon as possible would help save any electronics that may short due to the salt water.
Also being salt water, I would be inclined to clean as much as I could with denatured alcohol. That should clean things up, remove any salt left through evaporation, displace the water and it evaporates quickly. My concern would be without thorough cleaning, evaporation would leave salts behind that would eventually corrode any metal (copper on boards, motor windings, etc) over time and result in a 'catastrophic failure" while flying.