Yes, I have done it many times. If from the beach make sure to soak a while to remove salt, maybe even pour boiling water over a few times. I got a heap of great wood from a dry creek bed during the drought at my sisters property, and have also got it from under water. Just clean it up, remove any loose bark etc. and there you go. Beware of any trees with sap still in them, can be poisonous. If in doubt put wood into a container/tank etc. with some cheap fish (you could catch yourself some Gambusia AKA Mosquito Fish) to see what happens.
Cheers,
Ken.
Cheers,
Ken.

