Categories

Nomenclature of geomorphic features are based on definitions endorsed by the International Hydrographic Organization (IHO, 2001).^[5]

• Apron:
  Gently dipping featureless surface, underlain primarily by sediment, at the base of any steeper slope.
• Bank, sandbank:
  Shallow water or submerged bank of sand in a sea or river that may be exposed at low tide
• Basin; terrace; plateau:
  Depression, characteristically in the deep sea floor, more or less equidimensional in plan and of variable extent;
  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;
  Flat or nearly flat area of considerable extent, dropping off abruptly on one or more sides.
• Canyon:
  A relatively narrow, deep depression with steep sides, the bottom of which generally has a continuous slope, developed characteristically on some continental slopes.
• Continental rise
• Deep; escarpment:
  Generally depths greater than 6,000 m; Elongated and comparatively steep slope separating or gently sloping areas.
• Knoll:
  Relatively small isolated elevation of a rounded shape.
• Pinnacle:
  High tower or spire-shaped pillar of 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
• Reef:
  Rock lying at or near the sea surface that may constitute a hazard to surface navigation
• Ridge; sill:
  (a) Long, narrow elevation with steep sides. (b) Long, narrow elevation often separating ocean basins. (c) Linked major mid-oceanic mountain systems of global extent;
  Sea floor barrier of relatively shallow depth restricting water movement between basins.
• Seamount:
  Large isolated elevation, greater than 1000 m in relief above the sea floor, characteristically of conical form.
• Shelf; abyssal plain:
  A gently sloping, flatter region adjacent to a continent (or around an island) or at abyssal depths.
• Slope:
  A sloped area seaward from the shelf edge to the upper edge of a continental rise or the point where there is a general reduction in slope.
• Trench; saddle:
  Long narrow, characteristically very deep and asymmetrical depression of the sea floor, with relatively steep sides;
  Broad pass, resembling in shape a riding saddle, in a ridge or between contiguous seamounts.