Hydrographic features are objects which are noteworthy to ships in offshore waters. They include various obstructions and other significant man-made or natural objects such as buoys, wrecks or other dangers to navigation, reefs, piers, landmarks, navigational aids, etc. The cartographic codes for depths and features contained in NGDCs hydrographic surveys databases are listed below, and are also contained in file hyddas.ccd on the CD/DVD.
CARTOGRAPHIC CODES (Depths/Hydrographic Features)
056 Oil or gas well
089 Rock or coral head (depth known or unknown)
090 Wire-drag clearance
098 Wreck
111 Platform - oil or gas
165 Rock or coral head (estimated depth)
232 Deadhead
248 Platform (survey)
249 Platform (oil or gas), lighted
278 Dolphin
279 Pile
280 Pipe
281 Stake
282 Stump
283 Snag
284 Obstruction
367 Sounding, labeled hard
711 SOUNDING (METERS AND TENTHS)
957 Rock - Side scan sonar depth
961 Wreck - Side scan sonar depth
967 Obstruction - Side scan sonar depth
988 Islet