Some 2,500 people took off their clothes on Saturday to pose for US photographer/artist Spencer Tunick at Sydney's Bondi Beach in an effort to raise awareness about skin cancer.

Tunick, known for staging mass nude photo shoots at world landmarks, used a megaphone to direct attendees into several poses on the beach before many took a naked dip in the ocean.

The New York-based artist collaborated with a charity on the naked art installation in a bid to raise awareness about melanoma, Australia's fourth most common form of cancer.