Pondicherry Park is a 66 acre jewel near downtown Bridgeton. There's a pretty extensive trail system with a beautiful covered bridge at the northern entrance. The trails wind past wetlands, streams, and stone walls, but the highlight is the excellent low ropes course built on the abutting property of the Maine Lakes Science Center. Online info on the low ropes course is a little sparse, but just look for the Pinehaven Loop trail and you can't miss it. The ropes course is divided into several (5 or 6?) segments along the trail with all kinds of balance challenges, swinging ropes, and climbing structures. All age kids will love it. The adults might think they'll just "observe", but pretty soon the whole family will be climbing and swinging.
And, bonus, if you arrive at the trail head and your kid announces he forgot to wear shoes, you can dash into Reny's for a replacement pair.
Note: Dogs not allowed on most of the Pondicherry Park trails.