Mission Green Sri Lanka engages local communities and especially young people in environmental projects, including mangrove planting, beach and river cleanups to combat plastic pollution, amongst other projects on land and sea.

Moidjio is a Comorian research and conservation group which focuses on cetacean and turtle conservation projects, undertaking acoustic, cetacean monitoring and turtle monitoring projects. They also work to stop poaching of sea turtles on the islands and develop a sustainable ethical whale watching industry. They are working on humpback whales, spinner dolphins, green and hawksbill turtles, lemurs, mangroves, seagrass meadows and coral reefs. Their work includes tree planting to protect against erosion, research into mangroves, sea grass and coral reefs. They study sea and terrestrial birds, lemurs and Livingston bats on the islands; plus education programmes in sustainability and English in the local communities.

The Mediterranean Monk Seal remains one of the most endangered marine mammals in the world. The Monk Seal Alliance (MSA) was launched in 2019 by its founding Member organizations: the Prince Albert II of Monaco Foundation, the MAVA Foundation, the Segré Foundation, the Sancta Devota Foundation and the Thalassa Foundation, to leverage existing actions and step up concrete monk seal conservation efforts, including: information exchange, networking and collaboration among experts; contributing to implementing existing regional strategies and national action plans through co-funding collaborative projects; mobilizing other philanthropist organizations; and helping to coordinate efforts on monk seal conservation

In 2016, DMAD Marine Mammals Research Association initiated a conservation effort called Montenegro Dolphin Research in order to highlight the necessity of transboundary cetacean conservation between Montenegro and its neighbouring countries. MDR undertakes a year-round survey effort in the coastal waters of Montenegro to collect knowledge on distribution patterns and encounter rates of the bottlenose and striped dolphins. The research also targets photo identification in order to define the residency patterns in Montenegro. MDR aims to encourage community development through the active involvement of a wide range of stakeholders from fishermen to early career researchers and volunteers, with the aim of engaging the public in conservation, and to understand the benefit of environmental cooperation.

This non-profit public aquarium in Monterey, California, is known for its regional focus on the marine habitats of Monterey Bay, it was the first to exhibit a living kelp forest when it opened in October 1984. Its biologists have pioneered the animal husbandry of jellyfish and it was the first to successfully care for and display a great white shark. The organization's research and conservation efforts also focus on sea otters, various birds, and tunas. Seafood Watch, a sustainable seafood advisory list published by the aquarium beginning in 1999, has influenced the discussion surrounding sustainable seafood.

Morigenos' focus is on the study and preservation of cetaceans, including dolphins and sea turtles, and their ecosystems in the Northern Adriatic sea, through knowledge, conservation and awareness actions. They run dolphins research courses for members of the public.

Mote Marine Laboratory’s main campus is in Sarasota, Florida, where the Mote Aquarium plays an important role in Mote’s outreach efforts to educate visitors about marine life. This includes by 'presenting exhibits and programs that reflect ongoing research in the laboratory and that stimulate curiosity, discovery, exploration and stewardship of aquatic environments'. The laboratory has numerous marine research programmes, and aims to ' advance marine science and education, supporting conservation and sustainable use of marine resources.'

The Northland-based Mountains to Sea Conservation Trust was established in 2002, as a charitable umbrella for the Experiencing Marine Reserves (EMR) marine education and Whitebait Connection (WBC) freshwater education programmes. 

Mr. Trash Wheel is a stationary vessel positioned in the Baltimore River to catch marine debris before it reaches the harbour. Powered by its water wheels and solar panels, it is operated by a human crew.

Mwambao’s mission is facilitating a network linking coastal communities and other partner stakeholders that builds community resilience and improved sustainable coastal resource management and livelihoods. The network currently has eight member villages located in Unguja, Pemba, Tanga, Bagamoyo and Temeke Districts. Given the extensive marine resources in the area, attention is given to understanding the coastal marine ecosystems, improving fisheries management (with octopus an important catch) and an informed awareness of their natural resources in order to protect them in a sustainable manner. They have adopted Reef Ball technology to restore their coral reefs.

NAMMCO is an international regional body for cooperation on the conservation, management and study of marine mammals in the North Atlantic. The four partners are Faroe Islands, Greenland, Iceland and Norway. They have the aim of 'sustainable and responsible utilisation of all living marine resources, including marine mammals.' Through their cooperation under the umbrella NAMMCO, they 'aim to strengthen and further develop effective conservation and management measures for marine mammals'.

Neptune's Army of Rubbish Cleaners are volunteer divers who collect marine waste via cleanup dives in the UK. They work at raising awareness of the impact of marine debris, and on finding collaborative solutions to the problem of pollution in the oceans. With over 2000 cleanup dives, they are an award-winning conservation group.