Tall garden eels! Sorry this photo isn’t up to my usual quality, but it’s actually very impressive. It’s extremely hard to get photos of garden eels because they always quickly retract back down into their holes if you swim anywhere near them, so the photo has to be from a very polite distance, and they live in sandy flats down deep where there isn’t very much light.
This is pretty much exactly what it looks like when you are privileged enough to see them while diving, except that the sandy fields where they live are very very large and there are too many eels to even count. They fade into the distance all around you. And they don’t usually stick up this high when you are there!
But it always looks kind of murky and vague just like this, and you really really want to see them better, but just can’t because they are so shy and elusive.