International Convention for the Prevention of Pollution from Ships (MARPOL) (MARPOL)

The principal international treaty for preventing and minimising pollution from ships arising from routine operations and accidents.

MARPOL consists of the 1973 Convention as modified by the 1978 and 1997 Protocols and later amendments. Its six technical annexes address oil, noxious liquid substances in bulk, harmful packaged substances, sewage, garbage and air pollution and energy-efficiency measures.

Requirements and discharge controls depend on annex, vessel type, size, voyage, equipment, certification and designated special or emission-control areas. Flag and port states implement and enforce the treaty, and national or local rules may be stricter or cover vessels outside particular international thresholds.