I lifeguarded at a county park pool for 4 years. Basically a giant kid pool (no more than 6 feet deep at the deepest point (near the slide and only 5 feet deep where people could freely swim. Hence, NO DIVING!. Every 20 feet we had tiles showing a person diving and hitting their head on the bottom and red lines around the entire pool with "No diving" written in red lettering. I still had people asking me if they could dive...and these were adults as well. Afterawhile, I would just roll my eyes and point to the line and tiles.