They sit in old-fashioned halls or play pétanque in the surreal other world of naturist clubs. Britain's young naturists may be an endangered breed, but Laura Pannack, who won their trust by agreeing to take her clothes off before she photographed them, discovered an astonishing diversity of subjects.

Her quest to portray the secret lives of naturists under 30 has taken 18 months. After taking portraits in their homes, she obtained permission to photograph them in several naturist clubs, where photography is normally strictly forbidden. In these tranquil, anachronistic bubbles, screened from the uptight "textile" world (how naturists refer to the fully clothed), young naturists stand and chat in swimming pools or jump around the table tennis table under overcast skies.

There are 12,000 members of British Naturism, the UK's official organisation, but most are older adults. Pannack made contact with about 50 of the 300 young naturists and was astonished by the diversity within this small group, from young trendies to manual workers. Everyone she photographed "was a naturist for a different reason": some grew up with naturist parents; others discovered they enjoyed being naked privately, in their bedrooms; a few found like-minded souls on the internet.

Pannack found more young male naturists than female; the women she came across tended to come to it through their families or partners. She believes this is because single women feel more vulnerable and are unlikely to go alone to discover what a naturist club is like. Yet she found the clubs "respectable" and the atmosphere among young naturists "completely unsexual".

She photographed many of her subjects with possessions that were dear to them. "I wanted to show that these people weren't just naked. They were people," she says. "I didn't want to photograph their nudity. I wanted to photograph them."