Exactly, that;s the reason for the father's sage advice "no body, no crime." They would have needed a boat and some weights.
Like my daughter in the Cayman's told me, once you pass the barrier reef, it's "good-bye" if the body is weighted down, the fish take care of it within 3-5 days.
A boat and some weights? We're back to SC, the former dj/night watchman who slept on the Tattoo and must have had access to the water taxi.