My recommendation is to find a PADI Bubblemaker/Seal Team or SSI Rangers in your area as this is a pool only (6ft deep max) activity. Some shops will do these periodically so by the time your child reaches Jr. OW age, he has quite a few hours in the pool honing his skills and comfort level in the pool with scuba gear. If your local shops doesn't have a regular program, then you many have to contact a private instructor. Or better yet, get a group of about 4-6 of your child's friends to commit and I'm sure the shop will "$ee" the benefit of providing this activity. The biggest draw back shops have is rental gear in child sizes. It's a big investment without as much return as adult sized gear.
There are kids scuba summer camps not far from you which includes 8-15 yr olds,
Scuba Camp | Atlantic Edge Dive Center
or
http://www.learn2dive.net/educ_kids.asp
There are other options as well such as snuba:
http://submergedonline.com/kids-corner.html
If you are willing to travel, we loved Anthony's Key Resort in Honduras and they have a kids camp which includes a dolphin adventure (that's was coold for adults too):
http://www.anthonyskey.com/diving/diving-for-kids.htm
My 2 psi on the above given parental advise. I am not a parent, but I have been teaching scuba for 10 yrs and quite a few kids (several ScubaBoarders kids included). Most (not all as your child may be the exception) kids 8-10 don't have the attention span for more than some structured supervised underwater fun time. I have certified only a couple of 10 yrs olds and a few 11 year olds through out the years though I've had plenty more than that as students. Most were not really ready to complete a diving course. I prefer for the child to be at least 12 with a bit more maturity, they are starting to develop impulse controls.
One more important thing to consider, children's Eustachian tubes are not well developed until age 13 which leads to more equalization issues, ear aches, ear infections, etc. among these Jr. Divers. Kids have been ingrained to tough out mild sniffles/allergies, etc to not miss school and sometimes don't even mention it to their parents, then show up for class and can't clear their ears. All of the 10 & 11 y.o. I did eventually certify had ear issues at some point during their course.