Certified tour guides narrate informative waterfront excursions that provide magnificent views of the Manhattan skyline. Tours include the 90-minute Skyline, Twilight and NY History cruises. Times/prices vary. The hourlong Gateway to America Harbor Tour (daily at 10:30 a.m., noon, 1:30 & 3 p.m.; $18 adults, $16 seniors, $14 children ages 4-12) departs from Slip 5 in the Maritime Building (10 South St., btw Whitehall & Broad sts. Map 1, O7).