If that's freshwater, pull the battery, rinse it off with purified/demineralized water, and let it dry for two weeks, and it should be repairable, if not working. When it comes to fresh water, electronics are surprisingly durable. It's usually the current running through it that causes things to short and blow up. I've had a few RC planes and Traxxas RC nitro trucks end up in the drink, and they dry out to work again. Sometimes with minimal repairs/replacements.
Don't write it off just yet!