If you're looking for fun activities to do when you're visiting Hawaii, you should definitely try stand up paddle boarding. It's relatively easy to learn and is something that both kids and adults can enjoy. Once you've caught a few small waves, you'll be hooked!
There are tons of rental companies out there that also offer lessons, so shop around and look for the best deal. Also, be sure to check out water conditions before heading out. Stay safe out there and have fun!