The Mojave can do pretty well on wet salt sand if you use the High mineralization setting. As digger27 pointed out, this is not a miracle setting, but I was surprised at how well the machine did when I tried it on the west coast. It was stable over the wet sand, and did find me a couple of old coins. I can't remember what I had the sensitivity set at but don't think I had to set it really low.
I doubt the Mojave would do so well if the sand is mineralized (e.g., black sand), but if you want to hunt non-mineralized sand that's just wet with salt water, it'll probably do OK.
-Ken