Designated sea area where 0.10% sulphur cap applies — Baltic, North Sea, North America, US Caribbean, Mediterranean (from 2025).
In practice
Master ensures fuel switchover before crossing ECA boundary. Bunker logs and fuel-changeover record verifies the timing; PSC routinely samples this.
Regulatory detail & full definition
SOx Emission Control Area — designated sea region where the MARPOL Annex VI Reg. 14 fuel sulphur cap is 0.10% mass rather than the 0.50% global cap. Active SOx ECAs are the Baltic Sea, the North Sea (including the English Channel), the North American area extending 200 nm from the US and Canadian coasts, the US Caribbean ECA around Puerto Rico and the US Virgin Islands, and the Mediterranean Sea ECA effective 2025. Compliance is by low-sulphur fuel, EGCS, or LNG; bunker delivery notes evidence the fuel grade.