Undertow is the debut full-length album by American rock band Tool, released in 1993. According to Allmusic, Undertow helped heavy metal music and progressive rock remain prominent as a mainstream musical style, and allowed several later bands to break through to the mainstream. It was released at a time when grunge was at the height of its popularity, and pop punk was slowly beginning to gather mainstream attention. AllMusic saw the album's success in the "striking, haunting visuals that complemented the album's nihilistic yet wistful mood." It was eventually certified double platinum by the RIAA on May 14, 2001. , Undertow has sold 2,910,000 copies in the US.