Bay Street Theatre Main St & Bay St, Sag Harbor, NY11963 Bay Street Theatre is a 299-seat not-for-profit theater founded by Sybil Christopher, Stephen Hamilton and Emma Walton.…More Bay Street's Mainstage series features three plays and/or musicals a year with professional actors. Celebrities who have acted in or directed Mainstage plays include Alan Alda, Mercedes Ruehl, Darrell Hammond and Richard Kind. The "Literature Live!" series is geared toward middle and high school students and the plays are coupled with lesson plans. The Bay Street Picture Show screens classic films for just $5. The theater also offers workshops, children's theater camps and internships.