After two days of bad weather when we couldn't dive, the Quest 4000 ROV got back in the water today and made a dive at Niua South Volcano, the northern-most in the Tofua arc. The ROV explored a crater that was about 200 meters across and about 30 meters deep. At the center of the crater was a large sulfide mound, about 20 meters high and 50 meters wide, representing deposits formed during many years of high-temperature hydrothermal venting at this site. Most of the mound is now inactive but at the top we found a spectacular black-smoker vent, consisting of a cluster of about 20 active chimneys that had all grown together. The ROV sampled the vent fluids and gases coming out of the chimneys as well as a few pieces of the sulfides. Animals living at the vent included at least two species of shrimp, scaleworms, crabs, eelpouts, and barnacles.