MCS in Scotland is just as it says, the Scottish arm of the UK's Marine Conservation Society. They focus on marine conservation and fisheries management. MCS Scotland leads the Save Scottish Seas coalition to influence the Scottish Government and Scottish Parliament on all matters marine. This includes influencing policy and the law (Marine (Scotland) Act, and a fisheries strategy), creating 36 new MPAs including the largest in Europe, implementing a National Marine Plan, gaining protection for the most vulnerable inshore MPAs from fishing, influencing policy on plastic and other pollution.

The MECO Project is a Mediterranean collaboration between scientists and the public, including divers, fishermen and the general public, to research, learn, and conserve and improve protection for the sharks and rays of the Mediterranean Sea. MECO (Mediterranean Elasmobranch Citizen Observations) is essentially a network in which information is shared, engaging a wide audience and involving researchers from all over the Mediterranean. (Not to be confused with a marine insurance company amongst many other companies bearing the same word Meco in their title). Contact via Facebook.

MedPAN is the network of Marine Protected Areas managers in the Mediterranean. MedPAN gathers together 131 institutions and NGOs from 21 Mediterranean countries that either have direct responsibility for managing Marine Protected Areas (MPA) or are involved in the development of MPAs in the Mediterranean. These players manage or work with over 110 MPAS in 19 Mediterranean countries. The network exists since the 90s. It is run since 2010 by the MedPAN organisation, a permanent structure with dedicated funds established in late 2008.

Sea turtle nests are a sought-after, commercialized resource in Nicaragua and some beaches see poaching rates as high as 100%. To overcome this problem, the young Memanta team have established a scientifically-run hatchery to give the population a chance for survival. They also work on habitat protection measures, and ecotourism, with volunteers engaged in the turtle conservation programme.

MEPA Trust, established in 2015, is a core national mechanism for sustained financing to support local community environmental initiatives. These include projects with a focus on marine biodiversity (Project: Achieving Marine And Coastal Biodiversity Targets Through Local Action: Empowering Local, and Promoting And Supporting Biological And Cultural Diversity In Marine And Coastal Socio-Ecological Systems), mangrove restoration (Project: Barbuda Codrington Lagoon Mangrove Restoration Project), and restoration of Barbuda fisheries patrol boat.

​MOm, the Hellenic society for the study and protection of the monk seal acts for the protection and promotion of the coastal and marine environment of Greece, through the protection of the Mediterranean monk seal, which is the only seal species in the Mediterranean Sea and the most endangered seal on earth. It also has a Northern Aegean Dolphin Project. They work with volunteers in 5 key areas: Research, Rescue and Care, Protection and Management, Information and Awareness, and Environmental Education.

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.

As a collaborative research and conservation project, MWSP studies and protects whale sharks, while empowering local communities in Nosy Be, Madagascar. The scientific objective is to establish the occurrence, residency and population of the whale sharks in the area. The core elements of MWSPs research include monitoring the presence of whale sharks, as well as conducting in-water behavioural surveys and tourist compliance surveys in the area. MWSP also works closely with the local community by conducting capacity building activities and encouraging sustainable practices. Data is collected via a variety of methods, including free diving. Volunteers assist in this operation.

The Maldives Whale Shark Research Programme exists to facilitate whale shark research projects and to foster community focused conservation initiatives within the Maldives and throughout the Indian Ocean.

The Mangrove Association is a successful grassroots community organization that works to strengthen capacities, build skills, and advance agricultural practices to improve the quality of life of the population in the Bay of Jiquilisco, El Salvador, and in the process conserve the mangroves and the life they support for the benefit of the community. The association focuses on community organizing, food security, youth engagement, environmental conservation, and gender equality. The area they operate in is called the Bajo Lempa, located between the delta of the Lempa River and the Bay of Jiquilisco, in the municipality of Jiquilisco, department of Usulután. Jiquilisco Bay is a RAMSAR Wetland of International Importance and UNESCO Biosphere Reserve.