word | | Geography - note |
| Mandeb | Indian Ocean | major chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait |
| Mandeb | Somalia | strategic location on Horn of Africa along southern approaches to Bab el Mandeb and route through Red Sea and Suez Canal |
| Mandeb | Yemen | strategic location on Bab el Mandeb, the strait linking the Red Sea and the Gulf of Aden, one of world's most active shipping lanes |
| mangrove | Liberia | facing the Atlantic Ocean, the coastline is characterized by lagoons, mangrove swamps, and river-deposited sandbars; the inland grassy plateau supports limited agriculture |
| manmade | United States Pacific Island Wildlife Refuges | ... islands, which have been expanded by coral dredging; North Island (Akau) and East Island (Hikina) are manmade islands formed from coral dredging; the egg-shaped reef is 34 km in circumference; closed ... |
| March | Arctic Ocean | ... and western Russia; floating research stations operated by the US and Russia; maximum snow cover in March or April about 20 to 50 centimeters over the frozen ocean; snow cover lasts about ... |
| Mariana | Guam | largest and southernmost island in the Mariana Islands archipelago; strategic location in western North Pacific Ocean |
| marine | Arctic Ocean | ... to the Pacific Ocean via the Bering Strait); strategic location between North America and Russia; shortest marine link between the extremes of eastern and western Russia; floating research stations operated by the ... |
| marine | United States Pacific Island Wildlife Refuges | ... vines, and low growing shrubs; primarily a nesting, roosting, and foraging habitat for seabirds, shorebirds, and marine wildlife; closed to the public Johnston Atoll: Johnston Island and Sand Island are natural islands ... |
| maritime | Iran | strategic location on the Persian Gulf and Strait of Hormuz, which are vital maritime pathways for crude oil transport |
| Marmara | Turkey | strategic location controlling the Turkish Straits (Bosporus, Sea of Marmara, Dardanelles) that link Black and Aegean Seas; Mount Ararat, the legendary landing place of Noah's Ark, is in the far eastern ... |
| Marshall | Marshall Islands | the Marshall Islands Bikini and Enewetak are former US nuclear test sites; Kwajalein, the famous World War II battleground, is used as a US missile test range; island city of Ebeye is ... |
| Martin | Netherlands Antilles | ... and Sint Maarten) and the Windward Islands (southern) group (Bonaire and Curacao); the island of Saint Martin is the smallest landmass in the World shared by two independent states, the French territory ... |
| Martin | Saint Martin | the island of Saint Martin is the smallest landmass in the World shared by two independent states, the French territory of Saint Martin and the Dutch territory of Sint Maarten |
| Mary | Saint Helena | ... else in the world; Ascension is a breeding ground for sea turtles and sooty terns; Queen Mary's Peak on Tristan da Cunha is the highest island mountain in the South Atlantic ... |
| mass | World | ... Malaysia, and Indonesia. The islands of the Pacific are often lumped with Australia into a "land mass" termed Oceania or Australasia. Although the above groupings are the most common, different continental dispositions ... |
| massive | Zimbabwe | landlocked; the Zambezi forms a natural riverine boundary with Zambia; in full flood (February-April) the massive Victoria Falls on the river forms the world's largest curtain of falling water |
| Mawson | Heard Island and McDonald Islands | Mawson Peak on Heard Island is the highest Australian mountain (at 2,745 meters, it is taller than Mt. Kosciuszko in Australia proper), and one of only two active volcanoes located in Australian ... |
| maximum | Arctic Ocean | ... the extremes of eastern and western Russia; floating research stations operated by the US and Russia; maximum snow cover in March or April about 20 to 50 centimeters over the frozen ocean ... |
| maximum | Southern Ocean | ... extend entirely around Antarctica, reaching south of 60 degrees south near New Zealand and near 48 degrees south in the far South Atlantic coinciding with the path of the maximum westerly winds |
| May | Eritrea | strategic geopolitical position along world's busiest shipping lanes; Eritrea retained the entire coastline of Ethiopia along the Red Sea upon de jure independence from Ethiopia on 24 May 1993 |