After the boat crashes, call in an air strike on the specified location. Run up to the beach and move to the right to a small puddle at the right side of the beach. Stand in it briefly, then move towards the center of the beach to find a smaller puddle. Stand in that puddle briefly. Move towards the far left side of the beach. Stand briefly in the puddle in the barb wire. After several seconds the screen will shake and you will hear strange voices. Four lion statues will rise out of the ground with alien ray guns in their mouths.
If you just stand in the last puddle and not the others, you will still hear the weird voices and can get the ray guns.