A swimming Swimming Crab

(For licensing or usage, contact I was diving Waimea Bay on the North Shore of Oahu.  I came across a depression in the sand and went down to investigate it.  I found a crab (that goes by many names and is usually found around the shallow waters of the mangroves).  I started filming with my GoPro:   and finished recording it (displaying the typical defensive to move on).  All of a sudden, the crab swam straight up about 20 feet and then started swimming away.  It caught me by surprise and started recording again while trying to catch up to it.  I have never seen a crab do that.