Costs associated with the ship's employment, including costs of bunker fuel, canal tolls, light dues, port charges (including pilotage, towage, berth charges, agency fees, linesmen's charges, etc.), passenger-handling costs, and cargo- handling costs. Voyage costs are the costs incurred to earn the freight or other voyage revenue. They vary with the length of the voyage and the number of port calls.

A rule in major IMO conventions that, when inspecting a ship flying the flag of a State which is not a party to the Convention, Port State Control Officers must ensure that the treatment of such a ship and its crew is not more favourable than that of a ship flying the flag of a State party to that Convention. For example, many States have not yet ratified or acceded to MARPOL Annex VI, but ships flying their flags will still be required to meet the requirements of Annex VI to pass port State control inspections.