Join Date: May 2011
Location: north Wales
Thanked 12 Times in 12 Posts
Watersports, cycling, walking, bungee jumping...most of these have been suggested above.
Are they interested in nature? Some decent binoculars, and they might enjoy birdwatching, and if they have cameras they could photograph the wildlife they find.
get them scrapbooks, and encourage them to write about their experiences while away. They can stick in photos or any other interesting bits and pieces they find.
Find out if there are any local fairs or festivals on near where you are staying. They are free, and there's usually lots to see and do. Likewise, free concerts etc (plenty in Europe).
Get them a dog that likes to play and needs lots of walks...