I'm staying just north of Portsmouth for a week in May with DH, our two boys and DH's family. While we're there it will be DH's 40th birthday and I want to find something a bit unusual we can all do together on the day. He's quite active, would love something like canoeing, climbing or a water park, but it doesn't have to be sporty as long as it's a bit out of the ordinary. We'll have two (healthy and relatively active) 70-somethings, 4 other adults and 4 children ranging from 2 to 8 years old. We don't all have to join in for all of it but it would be good to find an activity we can all enjoy. Any recommendations from those of you local to the area?