word | | Terrain |
| March | Southern Ocean | ... 133 m); the Antarctic icepack grows from an average minimum of 2.6 million sq km in March to about 18.8 million sq km in September, better than a sixfold increase in area ... |
| margins | Austria | in the west and south mostly mountains (Alps); along the eastern and northern margins mostly flat or gently sloping |
| Mariana | Pacific Ocean | ... ocean floor in the eastern Pacific is dominated by the East Pacific Rise, while the western Pacific is dissected by deep trenches, including the Mariana Trench, which is the world's deepest |
| Mariana | World | the greatest ocean depth is the Mariana Trench at 10,924 m in the Pacific Ocean |
| marshes | Iraq | mostly broad plains; reedy marshes along Iranian border in south with large flooded areas; mountains along borders with Iran and Turkey |
| marshes | Togo | gently rolling savanna in north; central hills; southern plateau; low coastal plain with extensive lagoons and marshes |
| marshes | Turks and Caicos Islands | low, flat limestone; extensive marshes and mangrove swamps |
| marshland | Belarus | generally flat and contains much marshland |
| marshy | Estonia | marshy, lowlands; flat in the north, hilly in the south |
| marshy | Paraguay | grassy plains and wooded hills east of Rio Paraguay; Gran Chaco region west of Rio Paraguay mostly low, marshy plain near the river, and dry forest and thorny scrub elsewhere |
| Martinique | France | ... Grande-Terre is low limestone formation; most of the seven other islands are volcanic in origin Martinique: mountainous with indented coastline; dormant volcano Reunion: mostly rugged and mountainous; fertile lowlands along coast |
| massif | Heard Island and McDonald Islands | Heard Island - 80% ice-covered, bleak and mountainous, dominated by a large massif (Big Ben) and an active volcano (Mawson Peak); McDonald Islands - small and rocky |