Cocklebiddy Cave in Western Australia is iconic in the history of cave diving. For many years the longest underwater cave in the world, it has seen some heroic efforts at exploration over the last 40 years. In September 2015 the Cave Divers Association of Australia invited me to speak at their annual conference, and I was lucky enough to be able to incorporate a trip to Cocklebiddy Cave as a guest of the Wet Mules. The entire cave is wonderful, but sump 2 in particular is some of the most spectacularly beautiful underwater cave passage I have seen.