I'm suppose to finalize my pool drawing this week and dig hopefully next week. I am putting in a mini cave grotto and want people to be able to jump from the top of it if they want. I'm sure lots of kids will and some adults (including myself). I'm going to tell people no diving, but want to make sure my pool depth is deep enough just in-case some teenager does not listen. The top of the Grotto will be 4 ft high from the surface of the pool. I originally have a depth of 9 feet in the plans, but i'm unsure if that will be okay? Anyone have any experience jumping off something 4 feet above the pool surface and know how deep i should build my pool? My PB is unsure and i don't know how to figure this. I've researched everything about the diving envelops for boards and plat forms but can't find anything for a height of 4 feet.