What Is MARPOL Annex III? A Complete Guide to Harmful Substances Carried in Packaged Form

The carriage of harmful substances is not permitted unless it is carried out in accordance with the requirements of Annex III.

The regulation also requires Parties to establish detailed requirements relating to:

• Packing
• Marking
• Labelling
• Documentation
• Stowage
• Quantity limitations
• Exceptions

These requirements are intended to prevent or minimize pollution of the marine environment.

Another important point is that empty packages that previously contained harmful substances may themselves be treated as harmful substances, unless adequate precautions have been taken to ensure that no environmentally harmful residue remains.

The 11 Regulations of MARPOL Annex III

MARPOL Annex III contains 11 Regulations

Regulation 1: Definitions
Defines key terms, including harmful substances and packaged form, mainly by reference to the IMDG Code.

Regulation 2: Application
Requires harmful substances to be carried in accordance with Annex III requirements, including packing, marking, labelling, documentation, stowage, quantity limitations, and exceptions.

Regulation 3: Packing
Packages must be suitable for their contents and designed to minimize hazards to the marine environment.

Regulation 4: Marking and Labelling
Packages must be clearly and durably marked or labelled in accordance with the IMDG Code.

Regulation 5: Documentation
Ships must carry appropriate documentation, such as a special list, manifest, or stowage plan, identifying harmful substances on board.

Regulation 6: Stowage
Harmful substances must be properly stowed and secured to minimize risks to the ship, crew, and marine environment.

Regulation 7: Quantity Limitations
Certain harmful substances may be subject to quantity restrictions depending on their nature and the ship involved.

Regulation 8: Exceptions
Jettisoning harmful substances is generally prohibited, except when necessary for the safety of the ship or saving life at sea.

Regulation 9: Port State Control
Port State authorities may inspect ships where there are clear grounds to believe the crew is unfamiliar with essential Annex III pollution-prevention procedures.

Regulation 10: Application
Requires Parties to use the IMO Code for Implementation when fulfilling their Annex III responsibilities.

Regulation 11: Verification of Compliance
Provides for periodic IMO audits to verify that States are properly implementing Annex III.

MARPOL Annex III and the IMDG Code

Annex III provides the pollution-prevention framework, while the IMDG Code gives detailed requirements for classification, packaging, marking, labelling, documentation, stowage, segregation, and marine pollutant identification.

Key Point: Annex III and the IMDG Code should be used together for practical shipboard operations.

What Should Seafarers Check?

Before carrying harmful substances in packaged form, verify that:

• The substance is correctly identified and classified.
• Packaging is suitable and undamaged.
• Required marks and labels are displayed.
• Documentation is complete.
• Cargo is properly stowed and secured.
• Quantity limitations are followed where applicable.
• Relevant emergency procedures are understood.

Why MARPOL Annex III Matters?

A damaged package or lost container can release harmful chemicals directly into the sea.

Such pollution may affect:

• Marine organisms
• Coastal ecosystems
• Fisheries
• Water quality
• Human activities dependent on the marine environment

Annex III reduces this risk by establishing controls before cargo is loaded, during transportation, and while it is handled on board.

Conclusion

MARPOL Annex III provides the international framework for preventing pollution from harmful substances carried at sea in packaged form.

Although the Annex contains only 11 regulations, its practical importance is significant. It connects closely with the IMDG Code and addresses every major stage of transportation, from packing and identification to documentation, stowage, operational control, and compliance verification.

For seafarers involved in cargo operations, understanding Annex III is not simply a regulatory requirement. It is an essential part of preventing hazardous packaged cargo from becoming a source of marine pollution.

References

International Maritime Organization. (2024). International Maritime Dangerous Goods (IMDG) Code (Amendment 42–24). IMO.

International Maritime Organization. (2017). MARPOL Consolidated Edition 2017. IMO.