rocks wrecks and obstructions
Rocks
NOS
NIMA
IHO
Foreign NIMA Charts
Rock (islet) which does not cover, height above height datum
Rock (islet) which covers and uncovers, height above chart datum
Rock awash at the level of chart datum
Dangerous underwater rock of uncertain depth
Dangerous underwater rock of known depth
--in the corresponding depth area
--outside the corresponding depth area
Non-dangerous rock, depth known
Coral reef which covers
Breakers
