What do you do to during you period when you can't use tampons when you have to go swimming?

To swim during your period you should use internal sanitary products;

• Tampons
• Soft tampons
• Sponges
• Diaphragms
• Softcups
• Menstrual cups

Menstrual cups are the best option as they're safer and more hygeinic than tampons so pose no risks like TSS, infections or dioxin - thus they can be worn for 12 hours and with any flow so more convneient than tampons. For swimming as well as the advantage of being able to use during even light flow, cups also don't increase cramps or absorb water as tampons can, nothing shows outside the body, and they don't leak like tampons.

If you can't use internal sanitary products at all...

It's best not to swim - there's no situation where you have to swim, even something like a swimming exam can be re-scheduled if you're menstruating, it would be considered sexual discrimination if you were not allowed to re-schedule due to menstruation.

With very light flow you may be able to swim...

Menstrual flow doesn't stop in the water, this is a myth, however what little flow leaves the body will be diluted by the water so may go unnoticed* however heavier flow may be noticed especially if there is uterus lining along with blood, and especially as you get out of the pool.

* Menstrual flow is no more dirty or unhygienic than any other vaginal fluid, such as discharge, which can get in the pool any other time you swim. Pools are kept clean with filtration and chemicals to protect other swimmers, the concern during menstruation then is not with hygiene but with comfort for you and other swimmers...no one wants to swim through your menstrual blood, and I'm sure you don't want that to happen either.