TheInternational Maritime Organization (IMO;French:Organisation maritime internationale;Spanish:Organización Marítima Internacional)[1] is aspecialized agency of the United Nations regulatingmaritime transport.[2] It was established following agreement at a UN conference held inGeneva in 1948,[3] but this did not come into force for ten years,[4] and the new body, then called the Inter-governmental Maritime Consultative Organization, first assembled on 6 January 1959.[5][6] Headquartered in London, United Kingdom, the IMO has 176 Member States and three Associate Members as of 2025.[7]
The IMO's purpose is to develop and maintain a comprehensive regulatory framework for shipping and its remit includesmaritime safety, environmental concerns, andlegal matters. IMO is governed by an assembly of members which meets every two years.[2] Its finance and organization is administered by a council of 40 members elected from the assembly.[2] The work of IMO is conducted through five committees supported by technical subcommittees.[2] Other UN organizations may observe the proceedings of the IMO. Observer status is granted to qualified NGOs.[2]
IMO is supported by a permanent secretariat of employees who are representative of the organization's members. The secretariat is composed of aSecretary-General elected by the assembly, and various divisions such as those for marine safety, environmental protection and a conference section.[2]
Opening and anniversary plaques of QueenElizabeth II and model ofQueen Mary 2 in the lobby of the IMO Headquarters
In February–March 1948 the United Nations Maritime Conference in Geneva institutionalized the regulation of the safety of shipping into an international framework.[2] Hitherto such international conventions had been initiated piecemeal, notably theSafety of Life at Sea Convention (SOLAS), adopted in 1914 following theTitanic disaster.[1] The conference resolved "that an international organization to be known as the Intergovernmental Maritime Consultative Organization shall be established"; however many countries did not trust the convention, so ratification was slow and it took until March 1958 until it came into force.[5]
TheInter-Governmental Maritime Consultative Organization (IMCO; now using the hyphen) held its first Assembly in London in January 1959.[8] Its initial task was to update the SOLAS; the resulting 1960 International Convention for the Safety of Life at Sea was recast in 1974 and subsequently modified and updated to adapt to changes in safety requirements and technology. Since 1978, every last Thursday of September has been celebrated as World Maritime Day.[9]
As oil trade and industry developed, many people in the industry saw a need for further improvements in regards to pollution prevention. This became increasingly apparent in 1967, when the tankerTorrey Canyon ran aground entering the English Channel and spilled record-breaking 120,000 tons of crude oil.[10] This incident prompted a series of new conventions.[10]
IMO held an emergency session of its council to deal with the need to readdress regulations pertaining to maritime pollution. In 1969, the IMO Assembly decided to host an international gathering in 1973 dedicated to this issue.[10] The goal was to develop an international agreement for controlling general environmental contamination by ships when out at sea. During the next few years IMO brought to the forefront a series of measures designed to prevent large ship accidents and to minimize their effects. It also detailed how to deal with the environmental threat caused by routine ship duties such as the cleaning of oil cargo tanks or the disposal of engine room wastes. By tonnage, the aforementioned was a bigger problem than accidental pollution.[10] The most significant development to come out of this conference was theInternational Convention for the Prevention of Pollution from Ships, 1973 (MARPOL). It covers not only accidental and operational oil pollution but also different types of pollution by chemicals, goods in packaged form, sewage, garbage and air pollution.[4] The original MARPOL was signed on 17 February 1973, but did not come into force due to lack of ratifications. The current convention is a combination of 1973 Convention and the 1978 Protocol. It entered into force on 2 October 1983. As of December 2025, 162 states, representing 98.89 per cent of the world's shipping tonnage, are signatories to the MARPOL convention.[11]
In November 1975, the IMCO Assembly, as a part of comprehensive review of the Convention, decided to rename it as theInternational Maritime Organization (IMO); after ratifications, this happened in May 1982. Throughout its existence, the IMO has continued to produce new and updated conventions across a wide range of maritime issues covering not only safety of life and marine pollution but also encompassing safe navigation, search and rescue, wreck removal, tonnage measurement, liability and compensation, ship recycling, the training and certification of seafarers, and piracy. More recently SOLAS has been amended to bring an increased focus on maritime security through theInternational Ship and Port Facility Security (ISPS) Code. The IMO has also increased its focus on smoke emissions from ships. In 1983, the IMO established theWorld Maritime University in Malmö, Sweden and also facilitated the adoption of theIGC Code.[2] In 1991, the IMO facilitated the adoption of theInternational Grain Code.[2]
In December 2002, new amendments to the 1974 SOLAS Convention were enacted by the IMO. These gave rise to theInternational Ship and Port Facility Security (ISPS) Code, which went into effect on 1 July 2004. The concept of the code is to provide layered and redundant defences against smuggling, terrorism, piracy, stowaways, etc. The ISPS Code required most ships and port facilities engaged in international trade to establish and maintain strict security procedures as specified in ship and port specific Ship Security Plans and Port Facility Security Plans.[citation needed]
The IMO headquarters is a large purpose-built building facing theRiver Thames on theAlbert Embankment, inLambeth, London.[16] The organization moved into its new headquarters in late 1982, with the building being officially opened by QueenElizabeth II on 17 May 1983.[16] The architects of the building were Douglass Marriott, Worby & Robinson.[17] The front of the building is dominated by a seven-metre high, ten-tonne bronze sculpture of the bow of a ship, with a lone seafarer maintaining a look-out.[17] The previous headquarters of IMO were at 101Piccadilly (now the home of theEmbassy of Japan), prior to that at 22Berners Street inFitzrovia and originally inChancery Lane.[8]
The IMO consists of an Assembly, a Council and five main Committees.[2] The organization is led by a Secretary-General.[2] A number of Sub-Committees support the work of the main technical committees.[18]
The IMO wall honouring former Secretaries-GeneralFrom the left: Incoming Secretary-General Kitack Lim with predecessors O'Neill, Mitropoulos and Sekimizu, December 2015
The governing body of the International Maritime Organization is the Assembly which meets every two years. In between Assembly sessions a Council, consisting of 40 Member States elected by the Assembly, acts as the governing body. The technical work of the International Maritime Organization is carried out by a series of Committees. The Secretariat consists of some 300 international civil servants headed by a Secretary-General.[19]
The Secretary-GeneralArsenio Dominguez took office for a four year term on 1 January 2024, having been elected in July 2023.[20] The previous Secretary-General wasKitack Lim from South Korea elected for a four-year term at the 114th session of the IMO Council in June 2015 and at the 29th session of the IMO's Assembly in November 2015. His mandate started on 1 January 2016. At the 31st session of the Assembly in 2019 he was re-appointed for a second term, ending on 31 December 2023.[21][22]
TheFacilitation Committee, to simplify the documentation and formalities required in international shipping.[2][25] The Committees meet once or twice a year attended by Member States and NGOs.[25]
It is regulated in the Article 28(a) of the Convention on the IMO:
ARTICLE 28
(a) The Maritime Safety Committee shall consider any matter within the scope of the Organization concerned with aids to navigation, construction and equipment of vessels, manning from a safety standpoint, rules for the prevention of collisions, handling of dangerous cargoes, maritime safety procedures and requirements, hydrographic information, log-books and navigational records, marine casualty investigation, salvage and rescue, and any other matters directly affecting maritime safety.
(b) The Maritime Safety Committee shall provide machinery for performing any duties assigned to it by this Convention, the Assembly or the Council, or any duty within the scope of this Article which may be assigned to it by or under any other international instrument and accepted by the Organization.
(c) Having regard to the provisions of Article 25, the Maritime Safety Committee, upon request by the Assembly or the Council or, if it deems such action useful in the interests of its own work, shall maintain such close relationship with other bodies as may further the purposes of the Organization
The main Plenary Hall of the IMO, where the Maritime Safety Committee meets
The Maritime Safety Committee is the most senior of these and is the main Technical Committee; it oversees the work of its nine sub-committees and initiates new topics. One broad topic it deals with is the effect of the human element oncasualties; this work has been put to all of the sub-committees, but meanwhile, the Maritime Safety Committee has developed a code for the management of ships which will ensure that agreed operational procedures are in place and followed by the ship and shore-side staff.[19]
To join the IMO, a state ratifies a multilateralConvention on the International Maritime Organization. As of 2025, there are 176[26] member states of the IMO, which includes175 of the UN member states plus theCook Islands. The first state to ratify the convention was Canada in October 1948, but it took until March 1958 when Egypt and Japan brought the number of parties to 21, required by the Convention.[5]
These are the current members with the year they joined:
In 1961, the territories ofSabah andSarawak, which had been included through the participation of United Kingdom, became joint associate members;[27] in 1963 they became part ofMalaysia.[28]
The most recent new members areArmenia (landlocked, January 2018),Nauru (May 2018),Botswana (landlocked, October 2021)[7][29][30] and, on 27 February 2024, landlockedKyrgyzstan became the 176th Member State of the organization.[31]
Most UN member states that are not members of IMO are landlocked countries. These include Afghanistan, Andorra, Bhutan, Burkina Faso, Burundi, Central African Republic, Chad, Eswatini, Laos, Lesotho, Liechtenstein, Mali, Niger, Rwanda, South Sudan, Tajikistan and Uzbekistan. TheFederated States of Micronesia, an island-nation in the Pacific Ocean, is also a non-member.Taiwan, asRepublic of China, was a member of the IMCO from 1958[32] untilUN changed its recognition to People's Republic of China in 1971; its later attempts to join IMO were blocked, although it has a major shipping industry.
IMO is the source of approximately 60 legal instruments that guide the regulatory development of its member states to improve safety at sea, facilitate trade among seafaring states and protect the maritime environment. The most well known is theInternational Convention for the Safety of Life at Sea (SOLAS), as well asInternational Convention for the Prevention of Pollution from Ships (MARPOL). Others include the International Oil Pollution Compensation Funds (IOPC).[33] It also functions as a depository of yet to be ratified treaties, such as the International Convention on Liability and Compensation for Damage in Connection with the Carriage of Hazardous and Noxious Substances by Sea, 1996 (HNS Convention) and Nairobi International Convention of Removal of Wrecks (2007).[34]
IMO regularly enacts regulations, which are broadly enforced by national and local maritime authorities in member countries, such as theInternational Regulations for Preventing Collisions at Sea (COLREG). The IMO has also enacted aPort state control (PSC) authority, allowing domestic maritime authorities such ascoast guards to inspect foreign-flag ships calling at ports of the many port states. Memoranda of Understanding (protocols) were signed by some countries unifying Port State Control procedures among the signatories.[2]
International Code of Signals – mandatory for carriage on ships and used for communications between all ships, including merchant vessels and naval vessels[48]
The Casualty Investigation Code – enacted through Resolution MSC.255(84), of 16 May 2008. The full title isCode of the International Standards and Recommended Practices for a Safety Investigation into amaritime casualty or incident.[54]
The IMO has a role in tackling internationalclimate change. The First Intersessional Meeting of IMO's Working Group on Greenhouse Gas Emissions from Ships took place in Oslo, Norway (June 2008), tasked with developing the technical basis for the reduction mechanisms that may form part of a future IMO regime to controlgreenhouse gas emissions from international shipping, and a draft of the actual reduction mechanisms themselves, for further consideration by IMO's Marine Environment Protection Committee (MEPC).[55] The IMO participated in the2015 United Nations Climate Change Conference in Paris seeking to establish itself as the "appropriate international body to address greenhouse gas emissions from ships engaged in international trade".[56] Nonetheless, there has been widespread criticism of the IMO's relative inaction since the conclusion of the Paris conference, with the initial data-gathering step of a three-stage process to reduce maritime greenhouse emissions expected to last until 2020.[57] In 2018, theInitial IMO Strategy on the reduction of GHG emissions from ships was adopted.[58]
In April 2025, the IMO's Marine Environment Protection Committee (MEPC) approved net-zero regulations for the global shipping industry to reach net-zero GHG emissions in the shipping industry by or around 2050.[59] The changes would require that from 2028,shipowners would be required to use cleaner fuels or face acarbon pricing mechanism.[60] However, in October 2025, at a 2nd extraordinary session, adoption of the amendments to MARPOL Annex VI to bring the regulations into force were delayed to a future session.[61][62][63]
The IMO has also taken action to mitigate the global effects of ballast water and sediment discharge, through the 2004Ballast Water Management Convention, which entered into force in September 2017.[64]
In April 2025, at the IMO MEPC 83 meeting, the IMO agreed to develop a legally binding framework for controlling and managing ships’biofouling to reduce the accumulation of marine organisms on the hulls of ships and thereby reduce the transfer of invasive aquatic species.[65] Controlling ship's biofouling also improves the environmental efficiency of ships by reducing drag resistance.[65]
IMO Secretary General Dominguez at the 2024 meeting of the Maritime Safety Committee
The IMO'se-Navigation system has harmonized marine navigation systems with supporting shore services, as available to seamen and shore-side traffic services called. An e-Navigation strategy was ratified in 2005, and an implementation plan was developed through three IMO sub-committees. The plan was completed by 2014 and implemented in November of that year.[66]
On 1 January 2011,ECDIS (Electronic Chart Display Information Systems) were made mandatory for new ships and for existing ships subject to a phased update process which was completed on 1 July 2018.[67][68]
In December 2023, the IMO adopted a resolution targeting "Shadow fleet" ("dark fleet") tankers that form a risk by undertaking illegal and unsafe activities at sea. Primarily working for Iran and Russia to breach international sanctions, the tankers, many of which are elderly and unreliable, often undertake mid ocean transfers in an attempt to evade sanctions. The resolution calls upon flag states to "adhere to measures which lawfully prohibit or regulate" the transfer of cargoes at sea, known as ship-to-ship transfers.[69]
In June 2025, the IMO adopted amendments toSOLAS Regulation V/23 on improvingpilot ladder safety, including associated new Performance Standards for pilot transfer arrangements (to take effect 1 January 2028).[70][68]
The IMOCape Town Agreement is an international International Maritime Organization legal instrument established in 2012, that sets out minimum safety requirements forfishing vessels of 24 metres in length and over or equivalent in gross tons.[71] As of 2022, the Agreement is not yet in force but the IMO is encouraging more member States to ratify the Agreement.[71]
^Roach, J. Ashley; Smith, Robert W. (22 June 2012).Excessive Maritime Claims. Leiden Boston: Martinus Nijhoff Publishers. p. 401.ISBN978-90-04-21773-7.
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