South of Rankin Bank
We passed through a narrow valley in the middle of Rankin Bank and spent some time side scanning the flats on the eastern side of the bank. The good news is that water visibility has improved a great deal, allowing us to get the ship in close and look at individual features.
South of Rankin, we began searching in the rough terrain to the west of a mud volcano where Carolyn and Argus are parked. We found some large round depressions in the ocean bottom and decided to investigate. On first pass, we scanned the sides and found a large hole over 500 feet across. On the next pass, we drove directly over the top and measured out to be 90 feet deep. I'll leave it to the scientists to identify what it was, because none of us on NR-1 know. I do know that on land we sometimes find sinkholes where the ground has fallen into an underground cavity. Maybe this is something similar and that escaping gas or water left a cavity under the sea that the ocean bottom fell into.