HRI is a collaborative international initiative that generates user-friendly tools to measure the health of the Mesoamerican Reef. The main goals of the Healthy Reefs Initiative are to: promote the adoption and application of Healthy Reefs indicators by managers, policy makers and other leaders concerned with the integrity of the Mesoamerican Reef Ecosystem; Standardize the analysis and interpretation of reliable scientific data to improve reef ecosystem management; and Serve as an open forum for information sharing and networking among science and conservation partners.

Healthy Seas was founded to tackle the ghost fishing phenomenon that is responsible for the needless death of marine animals. They remove waste from the seas, in particular fishing nets, which are then regenerated into new textile products such as socks, swimwear and carpets. They achieve this through cleanups with volunteer divers and by working with stakeholders of the fishing sector toward marine litter prevention. Since their inception, in 2013, Healthy Seas has collected 585 tons of waste nets. They currently have operations in the North Sea, the Red Sea, the Mediterranean, Adriatic and Baltic Seas and the Pacific Ocean.

The Hebridean Whale and Dolphin Trust works directly with local communities to ensure whales, dolphins and porpoises are protected and valued throughout Scotland’s west coast. Their programme of community based research and education encourages strong local stewardship and supports meaningful change for the conservation of Hebridean cetaceans and marine life.

HOAM is a group of concerned locals from the Helderberg region who plan to eliminate litter and give their beaches back to nature.

The Hellenic Centre for Marine Research is a governmental research organisation operating under the supervision of the General Secretariat for Research and Innovation (GSRI). It comprises three institutes: the Institute of Marine Biology, Biotechnology and Aquaculture (IMBBC), the Institute of Marine Biological Resources and Inland Waters (IMBRIW) and the Institute of Oceanography (IO). Its main areas of research include physical oceanography, marine geology, marine biology, fisheries, aquaculture, marine genetics, and inland waters. It also provides consulting services, offers educational programs and courses, and participates in international research projects. The two international standard aquaria and Hydrobiological Station of Rhodes, operating under the HCMR umbrella, aim to stimulate interest in, to develop and to spread knowledge about the marine environment mainly focusing in the Eastern Mediterranean area

HSA members work together 'to inspire, inform and engage the public, decision-makers and experts to support and strengthen high seas governance and conservation, as well as cooperating towards the establishment of high seas protected areas.' Their current priority is 'to ensure that an intergovernmental conference taking place at the United Nations from 2018-2021 for the development of a new legally binding treaty under the United Nations Convention on the Law of the Sea results in robust protection for marine biological diversity in areas beyond national jurisdiction.' The Alliance is currently made up of 40+ NGOs plus the International Union for the Conservation of Nature (IUCN).

HKDCS is the only conservation society dedicated to whales, dolphins and porpoises (cetaceans) of Hong Kong. Their work focuses around the Indo-Pacific humpback dolphin (known as Chinese white dolphin and pink dolphin) and Indo-Pacific finless porpoise. The numbers of these species are dropping rapidly, especially the humpback dolphins, from 250 in the 1990's, to 100 in 2009 to 32 in 2018. HKDCS promotes public awareness, preservation of habitats, raising standards of Hong Kong's whale watching activities and conducts research. They are involved in opposing reclamation projects such as for the airport third runway, bridges and large-scale artificial islands which destroy the habitat of dolphins and porpoises.

HK Shark Foundation is dedicated to raising awareness about shark conservation in Hong Kong, and the urgent need to stop the unsustainable consumption of ALL shark products, particularly shark fins. Their target audience includes schools, individuals, companies, organizers of social events including weddings, to persuade them to save the world's sharks starting from tackling the consumption of shark products. As they say, ‘With over 50% of the world’s shark fin being traded through Hong Kong alone, we have a rare opportunity through our local efforts to make a significant impact on a global scale.’

The HBSRC’s mission is to intervene when seals are in distress. They rescue injured, sick or orphaned seals and then rehabilitate and return them to their natural environment within the Cape Peninsula Metropolitan Region.

The I AM WATER Ocean Guardians Program aims to build an understanding of the interdependence of healthy humans and healthy oceans and to influence behaviours to protect our global seas. The programme is aimed at low-income children who live near the sea in South Africa.

The programme "International Oceanographic Data and Information Exchange" (IODE) of the "Intergovernmental Oceanographic Commission" (IOC) of UNESCO was established in 1961. Its purpose is to enhance marine research, exploitation and development, by facilitating the exchange of oceanographic data and information between participating Member States, and by meeting the needs of users for data and information products. The Ocean Data Portal (ODP) provides a one-stop shop approach to oceanographic data held by the IODE global network of 80 National Oceanographic Data Centres (NODCs), as well as to resources from other participating systems.

The IUCN Global Marine and Polar Programme (GMPP) has a team committed to effectively addressing key global challenges in the marine and polar environment. GMPP cooperates with other IUCN thematic and regional programmes and with the IUCN Commissions to ensure that marine and polar ecosystems are maintained and restored in their biodiversity and productivity, and that any use of the resources is sustainable and equitable.