How do you swim on your period?

To swim on your period you have to use internal sanitary products;

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

Menstrual cups are the best option for swimming.
Cups are interna like tampons but safer so no risks of TSS or infections - this means it's safe to wear cups for 12 hours, including before your period or with very light flow so more convenient than tampons. Menstrual cups also don't increase cramps, have anything showing outside your body, absorb water, or leak like tampons.

You cannot use pads when swimming.
In the water pads would become saturated with water so wouldn't be able to absorb any blood, even if they didn't become saturated the blood wouldn't flow down into the pad anyway while in the water. If you use disposable pads these would become very bulky in the water, come unstuck and fall apart too, so are all the more unsuitable.

Your period doesn't stop in the water.

It's a common myth that your period stops in water, it doesn't - if flow is light what little blood leaves your body may be diluted in the water so go unnoticed, but heavier flow and pieces of uterus lining may show in water or once you get out of the pool.

Menstrual flow is as clean and safe as vaginal discharge, and pools are kept clean with filters and chemicals to treat the water, thus it is not gross or any more unhygienic to swim during menstruation as any other time of your menstrual cycle. The problem of swimming on your period is that no one wants to swim through your menstrual blood, and you probably don't want people seeing your blood - thus using correct sanitary products to prevent menstrual flow showing in the pool is really important.