Abyssal mountains – Mountains on the seafloor at abyssal depths having a vertical relief of greater than 1,000 m within a search radius of ~25 km are termed “abyssl mountains” (Harris et al., 2014). They include discrete guyots, seamounts, ridges (classes that are superimposed over “mountains”) and other positive relief features.
Abyssal classification categories (after Harris et al., 2014). The percentage areas first line refers to percentage of ocean basin area and the second line (in brackets) refers to percentage of abyssal area.
| Ocean | Abyssal Plain Area km2 | Abyssal Plain Area% | Abyssal Hills Area km2 | Abyssal Hills Area % | Abyssal Mountains Area km2 | Abyssal Mtns. Area % |
| Arctic Ocean Abyssal | 2,068,570 | 15.9 (38.7) | 2,244,920 | 17.3 (42) | 1,036,060 | 7.98 (19.4) |
| Indian Ocean Abyssal | 21,772,790 | 30.5 (34.7) | 30,179,170 | 42.3 (48) | 10,859,500 | 15.2 (17.3) |
| Mediterranean and Black Sea - Abyssal | 612,870 | 20.3 (43.6) | 613,830 | 20.3 (43.7) | 179,220 | 5.93 (12.7) |
| North Atlantic Ocean Abyssal | 10,255,540 | 22.9 (30.4) | 16,477,470 | 36.8 (48.9) | 6,987,830 | 15.6 (20.8) |
| North Pacific Ocean Abyssal | 24,906,630 | 30.4 (36.2) | 29,676,230 | 36.2 (43.2) | 14,137,990 | 17.3 (20.6) |
| South Atlantic Ocean Abyssal | 10,033,650 | 24.8 (27.4) | 19,511,510 | 48.3 (53.3) | 7,031,560 | 17.4 (19.2) |
| South Pacific Ocean Abyssal | 22,648,400 | 26 (28) | 44,059,800 | 50.6 (54.4) | 14,299,470 | 16.4 (17.7) |
| Southern Ocean Abyssal | 8,565,270 | 42.1 (50.4) | 6,688,370 | 32.9 (39.3) | 1,749,840 | 8.6 (10.3) |
| All Oceans All Abyssal | 100,863,730 | 27.9 (32.9) | 149,451,310 | 41.3 (48.7) | 56,281,460 | 15.6 (18.4) |
References
Harris, P.T., MacMillan-Lawler, M., Rupp, J., Baker, E.K., 2014. Geomorphology of the oceans. Marine Geology 352, 4-24.
IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organisation and Intergovernmental Oceanographic Commission, Monaco, p. 32. http://www.iho.int/iho_pubs/bathy/B-6_e4_EF_Nov08.pdf