Keep in mind the ANSI standard is to have a diving board installed, which was not the question asked. That minimum appears to be 7'6" if the depth profile and widths are met. I don't know that there is a standard for what is asked, which is deck diving. I will say that it's more of a risk question of what you are willing to assume as the owner? 7' should be plenty for someone who knows how to dive. However, are you willing to take that chance for someone you don't know? FWIW, kids in the Atlanta area who do summer swim team are trained to dive in 3 1/2' of water from the shallow end deck for relays from about 8 years on up (younger kids have to jump), and in my 16 years living here I've never seen an injury. It's all about the training and understanding of angle of entry when diving. Note, swim meets are the only time our HOA allows diving from the shallow end, due to liability.