“The water is meant to represent gender and sexual fluidity,” Mr. Singh said, seated beneath a 1988 Herb Ritts portrait of Cindy Crawford. The women who would pose in that water — their limbs wrapped around one another in a balletlike pose — were not simply models but activists. One uses performance art and digital media to share stories about the H.I.V. epidemic. Another is an underwater dancer who promotes ocean conservation. The third, a Belgian artist, recently filmed herself walking naked through a Hasidic neighborhood of Brooklyn during a sacred holiday.