Safe transport of containers


Containers carry a vast array of different goods, from consumer good such as shoes and electronic devices, to chemicals and other raw materials. The largest container ships can carry more than 24,000 containers.

Containers lost overboard can be a serious hazard to navigation and safety at sea in general, in particular to recreational sailing vessels, fishing vessels and other small craft, as well as to the marine environment. The work of the Sub-Committee on Carriage of Cargoes and Containers (CCC) on detection of lost freight containers at sea is also relevant to the Organization's work on addressing marine litter.


How many containers are lost at sea each year?

The World Shipping Council (WSC), which has consultative status at IMO, has issued the results of its surveys on container losses.

The World Shipping Council (WSC) estimates that in 2022, 661 containers were lost at sea, out of 250 million transported.

Please find more information here.

IMO's work to prevent loss of containers or problems with containers

IMO has long been working to ensure the safe transport of containers, including through guidelines on container stowage; mandatory SOLAS requirements to provide the verified gross mass of a container before it can be loaded on a ship; and mandatory reporting of loss of containers (amendments to SOLAS and MARPOL Conventions to be adopted in 2024).

The work will continue through a new output on "Development of measures to prevent the loss of containers at seaʺ, which was approved by MSC 107 and is being coordinated by the CCC Sub-Committee. It is anticipated that all matters relating to loss of containers will be discussed under that output in a holistic manner, with a view to developing further relevant provisions starting in September 2024.

IMO has developed and adopted a number of requirements to ensure the safe carriage of containers and has also developed specific guidance for packing and securing of containers.

IMO's International Convention for the Safety of Life at Sea (SOLAS) includes, in its chapter VI on carriage of cargoes, requirements for stowage and securing of cargo or cargo units (such as containers).

The International Convention for Safe Containers (CSC) provides test procedures and related strength requirements for containers.

The International Maritime Dangerous Goods (IMDG) Code is a mandatory international code for the maritime transport of dangerous goods in packaged form, in order to enhance and harmonize the safe carriage of dangerous goods and to prevent pollution to the environment. The Code sets out in detail the requirements applicable to each individual substance, material or article, covering matters such as packing, container traffic and stowage, with particular reference to the segregation of incompatible substances.

IMO with the International Labour Organization (ILO) and the United Nations Economic Commission for Europe (UNECE), have developed a non-mandatory global code of practice for the handling and packing of cargo transport units, which can be equally applied to maritime and land transport. The 2014 IMO/ILO/UNECE Code of Practice for Packing of Cargo Transport Units (CTU Code), along with related informative material, can be downloaded here. The CTU Code is currently under revision by the three above-referred agencies with the assistance of the industry.

Also, IMO has also adopted the Code of Safe Practice for Cargo Stowage and Securing (CSS Code).

In connection to CTUs transport and at the request of IMO, the International Organization for Standardization (ISO) has revised relevant ISO standards (ISO 1161:Series 1 freight containers – Corner fittings – Specifications; and ISO 3874:2017: Series 1 freight containers – Handling and securing) in order to incorporate the most recent advances in container handling and securing equipment, taking account of the latest generation of container ships with design capacity in excess of 18,000 TEU and including design and strength characteristics for automatic twistlocks.

Non-declaration and misdeclaration of cargoes and its associated risks

Several issues concerning the maritime transport of goods in containers continue to be a concern for many States and other stakeholders, this included also non-declaration and misdeclaration of cargoes (including dangerous goods).

Potential Risks

There are a number of potential risks associated to the effect of non-declaration and misdeclaration of cargoes, which may compromise the safety on board containerships, causing major fire incidents, with regrettable loss of life, the total loss of the ship and its cargoes and irreversible damage to marine environment the following non exhaustive list is included below:

  • incorrect vessel stowage decisions;

  • re-stowage of containers (and resulting delays and costs), if the overweight condition is ascertained;

  • collapsed container stacks;

  • containers lost overboard (both those overweight and containers that were not overweight);

  • cargo liability claims;

  • chassis damage;

  • damage to ships;

  • stability and stress risks for ships;

  • risk of personal injury or death to seafarers and shore-side workers;

  • impairment of service schedule integrity;

  • supply chain service delays for shippers of properly declared containers;

  • lost revenue and earnings;

  • last minute shut-outs of confirmed, booked and available loads when the actual mass on board exceeds what is declared and the total cargo mass exceeds the vessel limit or port draft limit;

  • impairment of ship's optimal trim and draft, thus causing impaired vessel efficiency, suboptimal fuel usage, and increased emissions from ships;

  • liability for accidents and fines for overweight containers on roads, and resulting time and administrative efforts and costs to seek reimbursement from responsible parties; and

  • loss of revenue for customs authorities in cases where duties or tariffs are applied by weight measurement of a commodity.

Requirements for verification of the gross mass of the container

On 1 July 2016, requirements to verify the gross mass of a packed container entered into force under the International Convention for the Safety of Life at Sea (SOLAS). Knowing the accurate gross mass of a packed container is critical to ensure correct stowage and stacking and avoid collapse of container stacks or loss overboard. This is an important safety measure, which is aimed at saving lives and preventing injury and the destruction of property.

There has always been a requirement in SOLAS to declare the gross mass of cargo and containers, but the so-called VGM rule added an extra level requiring verification of the mass. This is to ensure that the mass declared is a true reflection of the gross mass of the packed container, in order to avoid injury, cargo damage, loss of containers, and so on.

The verified gross mass is a condition for loading a packed container onto a ship. A packed container, for which the verified gross mass has not been obtained sufficiently in advance to be used in the ship stowage plan, will be denied loading onto a ship to which the SOLAS regulations apply.

Who enforces the SOLAS VGM rule and other regulations?

Like other SOLAS provisions, the enforcement of the SOLAS requirements regarding the verified gross mass of packed containers falls within the competence and is the responsibility of the SOLAS Contracting Governments. Contracting Governments acting as port States should verify compliance with these SOLAS requirements. Any incidence of non-compliance with the SOLAS requirements is enforceable according to national legislation.

Liability for damage or pollution from containers lost overboard from a ship

IMO has adopted a comprehensive set of liability and compensation treaties, intended to cover liability and compensation for damage, such as pollution, caused by ships. Treaties which may be relevant in the case of claims related to containers include:

  • Nairobi International Convention on the Removal of Wrecks, 2007 (in force) - this treaty provides a sound legal basis for coastal States to remove, or have removed, from their coastlines, wrecks which pose a hazard to the safety of navigation or to the marine and coastal environments, or both. The treaty also covers any prevention, mitigation or elimination of hazards created by any object lost at sea from a ship (e.g. lost containers). The Convention makes shipowners financially liable and require them to take out insurance or provide other financial security to cover the costs of wreck removal. It also provides States with a right of direct action against insurers.

  • Convention on Limitation of Liability for Maritime Claims (LLMC), 1976, and its protocol (in force) - this treaty limits the liability for claims in respect of, inter alia, removal of the cargo or of anything that has been on board a ship.

  • International Convention on Liability and Compensation for Damage in Connection with the Carriage of Hazardous and Noxious Substances by Sea (HNS), 1996 (and its 2010 Protocol) - this treaty (when in force) will establish a two-tier system for compensation to be paid in the event of accidents at sea involving hazardous and noxious substances such as chemicals. It covers not only pollution damage but also the risks of fire and explosion, and preventive measures regarding these risks; and it covers loss of life or personal injury as well as loss of or damage to property. Read more here.

Does IMO recognize the potential problems related to marine litter?

Yes. IMO's Marine Environment Protection Committee (MEPC) in 2021 adopted its Strategy to address marine plastic litter from ships, which sets out the ambitions to reduce marine plastic litter generated from, and retrieved by, fishing vessels; reduce shipping's contribution to marine plastic litter; and improve the effectiveness of port reception and facilities and treatment in reducing marine plastic litter.

The Strategy sets a vision to "strengthen the international framework and compliance with the relevant IMO instruments, endeavouring to achieve zero plastic waste discharges to sea from ships by 2025".

Download the IMO Strategy to Address Marine Plastic Litter from Ships.

Read more here.

Where can I find out more?

Contact your national maritime Administration for specific advice and guidance contact points.

Visit the IMO webpage: Verification of the gross mass of a packed container and download the text of the SOLAS VGM regu lations.

Download the IMO Guidelines regarding the verified gross mass of a container carrying cargo.

Statistics on container trade 

For the latest statistics on container trade by sea, please go the UNCTAD Review of Maritime Transport series.