This really needs to be seen in detail: blackmagic view
My walk at dawn was a little different two mornings ago when I discovered 50 or so Hasidic men and boys at the Ocean Grove beach and pier. Many were swimming/wading in their normal clothes.
I don't know of any particular jewish holiday to explain this type of activity. The metaphor of baptism is ironic considering their choice of beach (Ocean Grove is entirely owned by Methodist Christians). All I can think of is that these boys were part of a summer camp and that this was a camp activity.