Hoku Water Sports is the place to rent surfboards if you are staying anywhere in Poipu, and can't or don't want to transport a surfboard. It is located at Ko'a Kea Hotel, right in the middle of some of the best surfing sites on the South Shore for beginners and intermediate surfers, so you can walk your board from Hoku to wherever you want to surf, and return it to Hoku until the next time you want to go out. They have a large inventory. The owner, Greg, is very knowledgeable and generous with advice about surfing anywhere on Kauai, and appears to be a very good instructor, though we did not take any lessons from him.