The Jellyfish Swimsuit is a special swimsuit which was given to Akane Tendo after she was declared the 10,000th terrible swimmer to visit Jellyfish Beach and nearly drown. The swimsuit gives the wearer excellent swimming abilities, which for Akane is a godsend as she is a lead weight in water. Despite appearing to be a rare item, this design of swimsuit is shown to have been given out a large number of other women at the start of the Long Distance Swimming tournament. There is also a male equivalent in the form of swimming trunks.
The swimsuit will disintegrate when dried out due to being made out of jellyfish and it can be assumed that the same can be said for the swimming trunks, although this is not shown.