Swimming is perfect for the luteal phase when you cannot do any heavy workouts due to the low oxygen levels in your body that occur due to the hormonal shifts.

How can you swim when you have your period?

You cannot swim using pads for obvious reasons - they will get soaked with water and fail. Menstrual cups and tampons are perfect if you prefer to swim during your period. You can also use special waterproof pants if you prefer not to use tampons or cups.

When you’re in the water the bleeding doesn’t stop but the flow gets lighter because the water pressure on your body counteracts the effect of gravity on the blood flow. When you get out of the water your period will flow normally again.

Water may relieve light cramping. However, you may need to avoid swimming if your cramps are too intense. If menstrual cramps often cause you to double over in pain, lose your breath or clutch your stomach suddenly, swimming could be unsafe.

Sources:

Can You Go Swimming During a Menstrual Cycle? livestrong.com

Planning Your Swim Around Your Menstrual Cycle? sportsadvice.decathlon.in