They can wash in if they don't get stuck on something. I found one on the beach peaking out from under a bunch of seaweed, it was lost just over a year before by Levi Siver while w'surfing at my beach in California. It had a little water in it, so things were pretty corroded but I was able to get the card out of it, rinsed it off, dried it, stuck it into my computer and it worked. It just showed Levi walking to the water, beach start, hit the first wave, then it was just showing sand on the bottom followed by sky thru the water, over and over again while it rolled along the bottom for as long as the battery lasted. I gave the card to a good friend of his and mine, who mailed to card to Levi, the camera and the case were toast.