That's a good question, because I recall it being stated that the ground around the Fishermen's Huts was like sinking sand. As you try to dig, it fills in right behind you and you just keep sinking. Whoever placed that cross there KNOWS something and has a guilty conscience. They are attempting to send a message without revealing themselves.
it is very common to see Crosses in the ground at sites of fatal traffic accidents in the US.....they don't seem to get removed, but are maintained much like flowers in a cemetary. the Cross on the beach might be the equivalent, placed by a tourist or even some local.