grayscale photo taken underwater of people swimming

I have a gopro, and use it sometimes. It doesn’t have any digital screen so I was just taking shots of whatever, and hoping something worked out. I usually take a while to decide to convert a photo to Black and White, but I thought immediately that this one had to be. It has an eerie feel to it, that intrigued me, kind of an unexpected uncomfortable feeling. The lack of heads doesn’t help.