Paddleboarding is an easy water sport to learn in Hawaii. After you get on your board, all you have to do is sit and paddle around the bay. For the slightly more adventurous soul, you can stand and paddle parallel to the shoreline, maybe even ride some of the gentle Waikiki waves to the beach.
There's no better place to try paddleboarding than on Waikiki Beach, where the waves are pretty regular and usually small. As long as you mind the more serious water-sport enthusiasts, you'll have a memorable day enjoying the views until the sun goes down.