CATSEA

1. gat: a natural or artificial passage or channel through shoals or steep banks, or across a line of banks lying between two channels. (IHO Hydrographic Dictionary, S-32, 5th Edition)
2. bank: an elevation over which the depth of water is relatively shallow, but normally sufficient for safe surface navigation. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
3. deep: in oceanography, an obsolete term which was generally restricted to depths greater than 6,000 m. (IHO Hydrographic Dictionary, S-32, 5th Edition)
4. bay: an indentation in the coastline.
5. trench: a long narrow, characteristically very deep and asymmetrical depression of the sea floor, with relatively steep sides. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
6. basin: a depression, characteristically in the deep sea floor, more or less equidimensional in plan and of variable extent. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
7. flat: a level tract of land, as the bed of a dry lake or an area frequently uncovered at low tide. Usually in plural.
8. reef: rock lying at or near the sea surface that may constitute a hazard to surface navigation. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
9. ledge: a rocky formation continuous with and fringing the shore. (IHO Hydrographic Dictionary, S-32, 5th Edition)
10. canyon: a relatively narrow, deep depression with steep sides, the bottom of which generally has a continuous slope, developed characteristically on some continental slopes. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
11. narrows: a navigable narrow part of a bay, strait, river, etc. (IHO Hydrographic Dictionary, S-32, 5th Edition)
12. shoal: an offshore hazard to surface navigation that is composed of unconsolidated material. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
13. knoll: a relatively small isolated elevation of a rounded shape. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
14. ridge: (a) A long, narrow elevation with steep sides. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition) (b) A long, narrow elevation often separating ocean basins. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition) (c) The linked major mid-oceanic mountain systems of global extent. Also called mid-oceanic ridge. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
15. seamount: a large isolated elevation, greater than 1000m in relief above the sea floor, characteristically of conical form. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
16. pinnacle: any high tower or spire-shaped pillar or rock or coral, alone or cresting a summit. It may extend above the surface of the water. It may or may not be a hazard to surface navigation. (IHO Hydrographic Dictionary, S-32, 5th Edition)
17. abyssal plain: an extensive, flat, gently sloping or nearly level region at abyssal depths. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
18. plateau: a flat or nearly flat area of considerable extent, dropping off abruptly on one or more sides. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
19. spur: a subordinate elevation, ridge or rise projecting outward from a larger feature. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
20. shelf: a zone adjacent to a continent (or around an island) and extending from the low water line to a depth at which there is usually a marked increase of slope towards oceanic depths. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
21. trough: a long depression of the sea floor characteristically flat bottomed and steep sided and normally shallower than a trench. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
22. saddle: a broad pass, resembling in shape a riding saddle, in a ridge or between contiguous seamounts. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
23. abyssal hills: a tract, on occasion extensive, of low (100-500m) elevations on the deep sea floor. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
24. apron: a gently dipping featureless surface, underlain primarily by sediment, at the base of any steeper slope. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
25. archipelagic apron: a gentle slope with a generally smooth surface on the sea floor, characteristically found around groups of islands or seamounts. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
26. borderland: a region adjacent to a continent, normally occupied by or bordering a shelf, that is highly irregular with depths well in excess of those typical of a shelf. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
27. continental margin: the zone, generally consisting of shelf, slope and rise, separating the continent from the abyssal plain or deep sea floor. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
28. continental rise: a gentle slope rising from the oceanic depths towards the foot of a continental slope. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
29. escarpment: an elongated and comparatively steep slope separating or gently sloping areas. Also called: scarp. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
30. fan: a relatively smooth, fan- like, depositional feature normally sloping away from the outer termination of a canyon or canyon system. Also called: cone. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
31. fracture zone: an extensive linear zone of irregular topography of the sea floor, characterized by steep-sided or asymmetrical ridges, troughs or escarpments. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
32. gap: a narrow break in a ridge or a rise. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
33. guyot: a seamount having a comparatively smooth flat top. Also called tablemount. (IHO Hydrographic Dictionary, S-32, 5th Edition and IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
34. hill: a small isolated elevation (see also abyssal hills). (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
35. hole: a local depression, often steep sided, of the sea floor. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
36. levee: a depositional embankment bordering a canyon, valley or deep-sea channel. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
37. median valley: the axial depression of the mid-oceanic ridge system. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
38. moat: an annular depression that may not be continuous, located at the base of many seamounts, islands and other isolated elevations. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
39. mountains: a large and complex grouping of ridges and seamounts. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
40. peak: a prominent elevation either pointed or of a very limited extent across the summit. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
41. province: a region identifiable by a group of similar physiographic features whose characteristics are markedly in contrast with surrounding areas. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
42. rise: (a) A broad elevation that rises gently and generally smoothly from the sea floor. (b) The linked major mid-oceanic mountain systems of global extent. Also called mid-oceanic ridge. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
43. sea channel: a continuously sloping, elongated narrow depression commonly found in fans or abyssal plains and customarily bordered by levees on one or both sides. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
44. seamount chain: several seamounts in linear or orcuate alignment. Also called: seamounts. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
45. shelf-edge: a narrow zone at the seaward margin of a shelf along which is a marked increase of slope. Also called: shelf break. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Ed.)
46. sill: a sea floor barrier of relatively shallow depth restricting water movement between basins. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
47. slope: the slope seaward from the shelf edge to the upper edge of a continental rise or the point where there is a general reduction in slope. (adapted from IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
48. terrace: a relatively flat horizontal or gently inclined surface, sometimes long and narrow, which is bounded by a steeper ascending slope on one side and by a steeper descending slope on the opposite side. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
49. valley: a relatively shallow, wide depression, the bottom of which usually has a continuous gradient. This term is generally not used for features that have canyon-like characteristics for a significant portion of their extent. Also called: submarine valley; sea valley. (IHO-IOC Publication B-6, Standardization of Undersea Feature Names, 2nd Edition)
50. canal: an artificial water course used for navigation.
51. lake: a large body of water entirely surrounded by land. (IHO Dictionary, S-32, 5th Edition, 2629)
52. river: a relatively large natural stream of water.
53. reach: a straight section of a river, specially a navigable river between two bends or an arm of the sea extending into the land (adapted from IHO Dictionary, S-32, 5th Edition, 4239)