Nozomi Tojo (Love Live!) heard of a submerged hole that people could dive in to explore what was inside.
Without an equipment though, Nozomi had to resort to a small rebreather that she had as she jump in with her clothes and bag.
She seems to be doing well and having a good time not needing to breath from the rebreather yet...until her jacket gets tangled and eventually torned apart.
Maybe it wasn't a good idea to come in fully clothed...