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Swimming Australia Official Period-Safe Swim Underwear.
Water blocked, period locked. Period-proof any swimsuit with the original UnderSwim: Invisible Period Swim Underwear. Available in G10-12(W4) to W18 for tweens, teens and adult women. Seamless design stays totally hidden under full bottom swimwear while absorbing the same as 3-4 tampons (15ml) of menstrual flow.
Material
85% Nylon / 15% Spandex
Absorbency
Absorbs 15. -20ml. Same as approx. 4 regular pads.
But Wait, There's More!
- Waterproof & chlorine-resistant
- Built-in leak-proof lining
- Invisible under race suits and swimwear.
- PFAS? Not on our watch. (OEKO-TEX® certified).
- Absorbs and locks in 3-4 regular pads of her period.
- Compliant with Swimming Australia 'Inclusive Swimwear Policy’Â
Why is UnderSwim the go-to period protection for women and girls when they're hitting the water?

WATER RESISTANT COATING
Outer coating keeps water out, while the tech layers of inner lining lock her flow in.
INVISIBLE UNDER SWIMWEAR
With seamless edges and a high leg rise, they stay hidden under any swimwear with regular bottom coverage.
SWIMMING AUS COMPLIANT
Compliant with Swimming Australia's 'Inclusive Swimwear Policy'.
SAME AS 4 PADS
Holds the equivalent of 2-3 tampons/ 4 regular pads with ZERO added bulk.
MADE TO LAST
Chlorine resistant coating stands up to pool treatments (but don't forget to rinse them straight after wear!)
FREE FROM PFAs
No harsh chemicals used.
WATER RESISTANT COATING
Outer coating keeps water out, while the tech layers of inner lining lock her flow in.
INVISIBLE UNDER SWIMWEAR
With seamless edges and a high leg rise, they stay hidden under any swimwear with regular bottom coverage.
SWIMMING AUS COMPLIANT
Compliant with Swimming Australia's 'Inclusive Swimwear Policy'.

SAME AS 4 PADS
Holds the equivalent of 2-3 tampons/ 4 regular pads with ZERO added bulk.
MADE TO LAST
Chlorine resistant coating stands up to pool treatments (but don't forget to rinse them straight after wear!)
FREE FROM PFAs
No harsh chemicals used.
UnderSwim: Invisible Leak-Locking Swim Undies Demo
How do they hold flow in but keep water out?
Watch this demo video to find out!
NEW ✨ UnderSwim G-Fit
NEW G-FIT (THONG)
Seamless cut stays totally hidden under cheekier swimwear while also covering all the "essentials".