Maui Scavenger Hunt items?

My extended family is going on vacation to Maui in a few weeks, we thought it would be fun to do a week long scavenger hunt of random objects (i.e. pink shell, take a picture with a surfer, umbrella from a drink). Do you guys have any good ideas? Participants are age 7-Adult and the only rule is "you cannot spend any money for any of the items/photos you have" Thanks!