Cute. The ending left me with a lot of unanswered questions

Why doesn't Ben want to go home? Who are the travelers every year? What will their families do if they're actually going on this grand adventure around the earth?

  but I don't want to be super critical since this is technically a middle-grade book. The art was beautiful and it's just a nice story of friendship and adventure. I would like to see an adult version of this-- I think it could be darker and a little more twisted.