A marina structure is a type of waterfront structure that provides docking and storage for boats. The most common marina structures are wharfs, piers, and boathouses. A WHARF is a long, narrow platform built along the shoreline, typically made of wood or concrete. A PIER is a raised platform extending from the shore into the water, usually supported by piles. A boathouse is a building located on the shoreline, used to store boats and other related equipment.