ROV Deep Discoverer places an unidentified sponge in the vehicle's sampling drawer. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2015 Hohonu Moana. Download larger version (jpg. 878 KB).
Dive 05 of the expedition was conducted today on a ridge that is southeast of Maro Reef. This dive was the deepest conducted during this cruise and its objective was to explore biological communities at depths that have never previously been explored inside Papahānaumokuākea Marine National Monument. The dive started on flat, lightly sedimented pavement at 4,829 meters. As the ROV moved westward towards the base of the ridge, a few animals were seen that included sea stars, sponges, a swimming cucumber, a shrimp, and an ophidiid fish, as well as a plastic cup. At the base of the wall, the substrate changed to pillow lava flows that were lightly covered with sediment. Many of these pillows were small, suggesting they came from a source close by. As the ROV moved up the slope, the density of animals remained very low, and included sea stars, sponges, polychaete worms, shrimps, an anemone, a hydroid, a stalked crinoid overgrown by hydroids, and an ophidiid fish. The ROV left the bottom after a total bottom time of two hours and 49 minutes, having covered a linear distance of 280 meters.