A bulk carrier is ocean-going vessel used to transport bulk cargo items such as iron ore, bauxite, coal, cement, grain and similar cargo. Bulk carriers can be recognized by large box-like hatches on deck, designed to slide outboard or fold fore-and-aft for enable access for loading or discharging cargo. The dimensions of bulk carriers are often determined by the ports and sea routes that they need to serve, and by the maximum width of the Panama Canal.