San Francisco–based surf shop Mollusk (718-218-7456) has washed up on Metropolitan Avenue, at River Street, in Williamsburg. The tiny store caters to purists with fifteen brands of surfboard, including the retro narrow-nose DANOs (from $1,275), as well as classic trunks ($44) from Birdwell Beach Britches, and legendary surfing DVDs like Morning of the Earth ($30). The hard-to-find shop operates more like a clubhouse than a retail operation: Once a month, the owners throw a block party and project surfing flicks on the giant oil tanks across the street. “I think of this place as a kind of library,” says co-owner Chris Gentile, who will happily explain the environmental virtues of the store’s cork and bamboo boards ($1,200) or update customers with local surf conditions.