The IPCC has been established by World Meteorological Organization (WMO) and United Nations Environment Programme (UNEP) to assess scientific, technical and socio-economic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation. Ocean acidification is one of many concerns within their focus.

The International Climate Initiative (IKI) is an important part of the German government international climate finance commitment. Since 2022, the Federal Ministry for Economic Affairs and Climate Action (BMWK) has been the lead ministry for the IKI. Since 2008, IKI has been financing climate and biodiversity projects in developing and newly industrializing countries, as well as in countries in transition. IKI focuses on four areas: mitigating greenhouse gas emissions, adapting to the impacts of climate change, conserving natural carbon sinks with a focus on reducing emissions from deforestation and forest degradation (REDD+), as well as conserving biological diversity, including in marine environments. Their significant contribution to marine environments is evident in the projects recorded in their impressively comprehensive website.

ICFC partners with local organizations to promote sustainable use of marine resources around the globe. Since 2007, they have been actively partnering on projects with local conservation organizations in Latin America, Africa and Asia. Their work is science based, and engages local communities to secure lasting conservation gains in priority areas, including turtles in Nicaragua, porpoises in Mexico, manta rays in the Philippines, amongst many others.

ICRAN is a collaborative effort working to halt and reverse the decline in health of the world's coral reefs; network of many of the world's leading coral reef science and conservation organisations. The network consolidates technical and scientific expertise in reef monitoring and management to create strategically linked actions across local, national and global scales. Part of the ICRI forum initiative.

The International Coral Reef Initiative (ICRI) is an informal partnership between Nations and organizations which strives to preserve coral reefs and related ecosystems around the world. Although the Initiative is an informal group whose decisions are not binding on its members, its actions have been pivotal in continuing to highlight globally the importance of coral reefs and related ecosystems to environmental sustainability, food security and social and cultural wellbeing. The work of ICRI is regularly acknowledged in United Nations documents, highlighting the Initiative's important cooperation, collaboration and advocacy role within the international arena. Both CORDIO and GCRMN are operational networks and programmes of ICRI, acting implementing arms of the initiative.

The International Society for Reef Studies (ISRS) was founded in 1980, after which membership increased rapidly as interest in and concern for coral reefs has grown. It is the principal learned society to which reef scientists and managers from across the world belong. The principal objective of the Society is to promote the production and dissemination of scientific knowledge and understanding of coral reefs, both living and fossil. To achieve its objectives the Society: 1. publishes and distributes the well-regarded scientific journal Coral Reefs (click here for ISRS member access) 2. coordinates the International Coral Reef Symposium (ICRS), a major scientific congress held every four years, typically attended by some 2000 delegates 3. promotes or supports smaller regional conferences or inter-congresses, in years between successive ICRS 4. publishes Briefing Papers and Statements on emerging issues related to coral reefs 5. distributes twice yearly a news journal / newsletter called Reef Encounter 6. acknowledges the scholarship and work of its members with Society awards and honours.

International Foundation for the Conservation of Natural Resources (IFCNR) says it is a non-profit independent foundation and 'the preeminent global advocate for issues, the resources themselves, as well as the nations, people, and industries involved with environmental issues.' However, according to Lobbywatch, IFCNR has traditionally focused on defending hunting, trapping and fishing but more recently GM has been added to its list of causes and it now has a website focusing specifically on this issue. The general IFCNR website and Facebook pages are not accessible at this time (2021, confirmed 2023)

IFAW is an international animal protection foundation. Amongst their many activities, they are involved in marine initiatives including anti-whaling and the protection of dolphins. It is one of the largest animal welfare and conservation charities in the world. The organization works to rescue individual animals, safeguard populations, preserve habitat, and advocate for greater protections. IFAW was instrumental in ending the commercial seal hunt in Canada. In 1983 Europe banned all whitecoat harp seals products. This ban helped save over 1 million seals. IFAW operates in over 40 countries

The IGFA is a non-profit organization committed to the conservation of game fish and the promotion of responsible, ethical angling practices, through science, education, rule making, record keeping and recognition of outstanding accomplishments in the field of angling.

Since 1982, the International Marine Mammal Project (IMMP) has been a global leader in protecting whales and dolphins and their ocean habitats. IMMP pioneered the Dolphin Safe tuna fishing standard, stopping the intentional chasing and netting of dolphins by many tuna companies and preventing tens of thousands of dolphin deaths annually. They continue to monitor more than 800 tuna companies to ensure they are following Dolphin Safe fishing practices that protect dolphins and other marine life. The organization campaigns to stop all trade in live dolphins and whales, to end the capture and captivity of whales and dolphins for circus performances; and to fight pollution and plastics in the ocean, particularly the entanglement of marine life in fishing gear. IMMP is an Earth Institute project.

Marinelife Alliance works on conservation and research for the betterment of the marine life along the coast of Bangladesh and in the marine territory of the Bay of Bengal.

IMO is the United Nations' specialized agency responsible for safety and security of shipping and the prevention of marine pollution by ships. IMO's Intervention Convention affirms the right of a coastal State to take measures on the high seas to prevent, mitigate or eliminate danger to its coastline from a maritime casualty. The International Convention on Oil Pollution Preparedness, Response and Co-operation (OPRC), 1990 provides a global framework for international co-operation in combating major incidents or threats of marine pollution. A protocol to this convention (HNS Protocol) covers marine pollution by hazardous and noxious substances.