Help.... need sentimental gift for nephew (age 9)

Hoping for some help with a touch question... My father died when I was in my early 20s. I don't have any close uncles and no brothers, but I do have a 9 year old nephew who is my only sibling's son. I have asked him to walk me down the aisle? Here's the question... my wedding is in 3 weeks and I still cannot land on a gift for him. He's kind of a surfer little dude (loves the ocean) and loves soccer. I wanted to get him a custom leather bracelet or a necklace where you can track sea animals or something that would be sentimental that he could keep forever but would be used. The only problem is finding a bracelet that will fit him (he's pretty small) OR a necklace that you can personalize without it looking girly. Any thoughts or suggestions? I could use all the help I can get! Thanks in advance.