Not all of the dancers are black and the dance floor is anywhere but underground, but BLACK UNDERGROUND has no identity crisis. These DJs who run the dance space on the boardwalk at Coney Island (3-9 p.m. Saturdays, late June through mid-September) would be as funky and all-inclusive by any other name. Stoned white hipsters, buff black lesbians, lonely Latins on a date with the ghost of Celia Cruz, mermaids newly crawled from the sea, even break dancers spinning barebacked on the boardwalk (ouch!)—all are welcome, in sight of the surf, the projects, the midway, Russian mafiosi down from Brighton Beach, God, and everybody else.