I wouldn’t even use the term “looting” to describe what’s going on there. If scavengers can recover pieces or wreckage from a shipwreck that’s 150 feet underwater, then the Royal Navy could have done it themselves at any time over the last 80 years. They obviously didn’t think it was something terribly important to their country over all that time.
Under international law sunken warships continue to be the property of their governments. You can salvage sunken civilian ships without anyone’s permission, but not sunken warships.