I'm looking for suggestions for a gift for my backpacking partner.

10 years ago he asked if I would be interested in going backpacking with him. Neither of us had any experience with it, but we both decided to go for it. Nearly 10 years later we've bushwhacked in Alaska, canoe camped in Canada, hiked in the alps, and hit up a bunch of other US locations.

This summer will be our 10th year of going (big trip this year is a multi day trek in Iceland). I kind of want to surprise him with something.

Neither of us need any more gear. I was hoping for something more sentimental. Any ideas?