The international definition of «water-resistant» is: 50% UV protection remains after a 2 x 20 minutes whirlpool bath.
«Extra water-resistant» sun protec-tion means: The UV protection is still 50% after a 4 x 20 minutes whirlpool bath. In other words: You can bathe twice as long when wearing «extra water-resistant» sun protection.
IMPORTANT: Even water-resistant products have to be re-applied after bathing and drying.
Only few sun protection products meets this requirement. These Louis Widmer products are up to this standard: