Harbor sights include tugboats, BUOYS, ferries, piers, SHIPS, and tankers. Tugboats are small, powerful vessels used to maneuver larger SHIPS in and out of ports. BUOYS are floating markers that indicate the location of hazards, channels, or navigational aids. Ferries are boats that transport passengers and vehicles across bodies of water. Piers are structures built out into the water to provide access to SHIPS. SHIPS are large vessels used for transportation of goods and people. Tankers are SHIPS designed to transport large amounts of liquid cargo.