A week or so before Christmas we were watching a documentary about the late Dean Potter and his attempt at the highest, untethered highline. All the kids shouted that they wanted to try slacklining. Fortunately I managed to get a basic slackline kit at a reasonable price and during the holidays we tried it out:

 

Lots more practice is needed but the kit fits nicely in a stuff sack and sits neatly in the bottom of my daypack so whenever we head to the woods we can practice. Fun for all the family!