Back in the late 70s we were anchored in the atoll of Ulithi and saw something similar…although not near as dense.
They were little reef sharks…like 3 or 4ft long…after a couple days we did get in the water with them to clean the bottom, and had no problems at all….it was bizarre.
Thanks for the link….cool.
S/V Arctic Lady
I love my boat, I can't afford not to!