There are plus sides to splashing around on your period. Hot baths can stimulate blood flow, which can ease cramps, according to Mayo Clinic . Plus, swimming in a pool or even jumping along with the waves in the ocean can be a form of exercise, which research has shown can reduce menstrual aches and pains . So feel free to spend some extra time submerged during your time of the monthit may not shorten your cycle, but it can make it less uncomfortable, which is a win.