We highly recommend the overnight Doubtful Sound tour with Real Journeys. They made it so easy for us, picking us up at our hotel in Queenstown and driving us to our bus. The driver was fantastic, as was our boat captain and crew. Very comfortable and entertaining. The sound was absolutely breathtaking and so peaceful. The highlight for sure was the kayak tour of the sound. We felt like we were at the end of the world (exactly what we were looking for). Waterfalls everywhere we looked. Informative tour guides. Highly recommended!