There are lots of walking options at HHI, including the bike trails which double as pedestrian walkways, as well. Something like 100 miles of them. I don't know if your 11-year old is capable of doing something like a parasailing, but that is available nearby. The wildlife refuge I mentioned would be an excellent spot as its acres upon acres of outdoors walking and seeing wildlife. The grounds at the main resort are lovely and include a butterfly garden and the yard games I mentioned: horseshoes (2 places), corn hole, giant checkers, bocce ball, and numerous hammocks where he could swing to his heart's content. Many of the restaurants on HHI have outdoor seating, and you could request a table on the periphery if you wished. In particular, a place like Skull Creek Boathouse has loads of outdoor seating though it offers no reservations. But, if you go at, say, 4PM you could probably easily sit outside and watch the full service marina to which it's attached. Same with Fishcamp on Broad Creek. They do take reservations, but have a large outdoor seating area including some chairs off the main floor where your son could flourish. I've also heard good things about the Sandbox Interactive Museum and the Coastal Discovery Museum. And the resort is so very calming and outdoorsy at the same time. A great place to be. I'm sure you will do some research, but I do believe HHI would be a superb place for all of you.