We loved every bit of our experience. From Max our tour guide to Kayaking (first time) to spending time at Hahei Beach.
Make sure to reach at least 15 mins before the tour starts. Wear comfortable quick dry clothes (may be go commando ;) ). Put a lot of sunscreen on your upper body. And most importantly leave all your worries behind and indulge in the experience as you can depend on the tour guide with your life.
P.S. There is free parking at the beach (if you book an early tour, then it's easy to find a spot but not so much later in the day)