MPAConnect is a learning network of MPA managers and professionals in the Caribbean. Since 2010, this partnership between the U.S. National Oceanic and Atmospheric Administration (NOAA), through their Coral Reef Conservation Program, and the Gulf and Caribbean Fisheries Institute (GCFI) has addressed MPA management capacity by building a network of some 32 MPAs from 11 countries and territories in the Wider Caribbean region. The network works to increase the effectiveness of MPA management by addressing specific capacity needs of individual MPAs through a variety of means, including regional peer to peer workshops, site-specific technical support, learning exchanges and direct grant funding.

MaREI is the SFI Research Centre for Energy, Climate and Marine research and innovation co-ordinated by the Environmental Research Institute (ERI) at University College Cork. The Centre comprises over 220 researchers focusing on defined global challenges such as the Energy Transition, Climate Action and the Blue Economy.

MaRHE is part of the University of Milan - Bicocca (Università degli Studi di Milano-Bicocca), with the purpose of carrying out research and educational activities in environmental science and marine biology, tourism science and human geography. Part of this is to educate on protection of the marine environment and its biodiversity, as well as to use and manage its resources responsibly. MaRHE works closely with the government of the Maldives on projects to promote sustainable fishing and protection of the coral reefs in the area.

Mangroves for the Future (MFF) is a partnership-based regional initiative which promotes investment in coastal ecosystem conservation for sustainable development. MFF focuses on the role that healthy, well-managed coastal ecosystems play in building the resilience of ecosystem-dependent coastal communities in Bangladesh, Cambodia, India, Indonesia, Maldives, Myanmar, Pakistan, Seychelles, Sri Lanka, Thailand and Viet Nam. The initiative uses mangroves as a flagship ecosystem, but MFF is inclusive of all types of coastal ecosystem, such as coral reefs, estuaries, lagoons, sandy beaches, sea grasses and wetlands. MFF is co-chaired by IUCN and UNDP. Confirmation required whether MFF is still active (July 2022)

Manta Matcher is a global online database for manta rays. It is one of the Wildbook Web applications developed by Wild Me, created in partnership with Dr. Andrea Marshall of the Marine Megafauna Foundation. Manta rays have unique spot patterning on their undersides, which allows for individual identification. Scuba divers upload their manta identification photographs to the Manta Matcher website, supporting global research and conservation efforts. Manta Matcher is a pattern-matching software. This citizen science tool is free to use by researchers worldwide.

The MAR Fund (Mesoamerican Reef Fund) was established in 2004 by representatives from conservation funds in the countries of the MAR region (Belize, Guatemala, Honduras, and Mexico) as a regional funding and coordination institution. It is a private fund intended to drive regional funding and partnerships for the conservation, restoration, and sustainable use of the Mesoamerican Reef. This includes: Saving our Sanctuaries (supports the establishment and protection of an interconnected network of priority coastal and marine protected areas in the region), Fishing for the Future (sustainable fisheries and the establishment of fisheries recovery areas) and Climate Change: The Need is Now (monitoring climate change effects on the reef and supporting adaptation to climate change).

Set up by Marine Biological Association of the UK, MarLIN is a resource which provides information for marine conservation, management, protection and planning, a centre of excellence in spatially based and time-series marine biological information and for good stewardship in the marine environment. The resources are based on available scientific evidence and designed for all stakeholders, from government agencies and industry to naturalists and the public. MarLIN hosts the largest review of the effects of human activities and natural events on marine species and habitats yet undertaken.

Based in Costa Rica, Panama and Columbia, MarViva Fundación is a regional, non-governmental and non-profit organization, whose area of ​​action is located in the Eastern Tropical Pacific, and which has the aim of conservation and sustainable use of marine and coastal resources through the management of human activities at sea.

Marevivo is a significant Italian environmental association that protects the sea and its resources, focusing in particular on biodiversity conservation, sustainable development, enhancement and promotion of marine protected areas, combatting pollution and illegal fishing. They promote education in schools and universities, and act as an advocate influencing law and policy with many successful campaigns in Italy, such as recently the ban of microplastics in rinse-off cosmetics and the ban on sea cucumber fishing. Marevivo relies on the work of hundreds of volunteers and thousands of members scattered all over Italy, with representation throughout the country in the form of delegations in more than 25 centres. They are organised into diving, sailing, canoe & kayak, beaches and shore divisions.

Marilles Foundation is dedicated to the conservation of the Balearic Sea and its coasts, and reconciling the conservation of marine ecosystems and economic prosperity. Working other foundations and private donors, their main source of funding comes from the Adessium Foundation. They coordinate local efforts and finance the most effective measures to conserve the Balearic Sea, including connecting those most prepared to carry out marine conservation projects with those who can finance them. Currently, their priorities are to: improve marine protected areas; secure sustainable fisheries; and promote marine education. They also support projects that reduce the impact of the boating and tourism industries, and of plastics and pollution.

The Marine Conservation Action Fund (MCAF), part of the New England Aquarium, is a microgranting program that addresses critical needs in the marine conservation field, by funding small-scale, high-impact projects around the globe. With each funded project, MCAF is helping to protect the health of marine species and habitats, and the communities that depend on them in low and middle-income countries. Since 1999, MCAF has supported many various projects, including researchers gathering key data on threatened and endangered animals, grassroots leaders engaging and educating communities through local conservation projects; and efforts to offer long-term protection for marine species and habitats.

Marine Conservation Institute is a non-profit scientific and conservation advocacy organization that has been working since 1996 to promote cooperation essential to protecting and restoring the Earth's biological diversity. From the headquarters in Seattle WA and the Washington DC and California offices, they work to protect marine life around the United States and beyond by encouraging research and training in marine conservation biology, bringing scientists together to examine crucial marine conservation issues, conducting policy research to frame the marine conservation agenda, leading outreach efforts to educate scientists, the public and decision makers on key issues, and building partnerships to solve problems affecting marine life and people.