Maritime salvage law??

I watched a US tv series and it stated that in America if someone’s boat sinks and you salvage it you are entitled to a substantial reward. i.e. someone’s boat sunk because of a hole in the side after a hurricane I patched it up with some wood and glue when the tide went out and I floated when it came back in. Here I would be entitled to a reward from the owner and if not I could have the vessel. Or if there was a load of jewellery in a box in a vessel wreck and I dived Down to get it I could keep it cause I salvaged it. You can do this without notifing the owner or receiving a contract. I was wondering can you do this in Ireland and what is the law??