| NOS/NIMA |
|
IHO/Foreign NIMA Charts |
| S |
Sand |
S |
| M |
Mud |
M |
| Cy; Cl |
Clay |
Cy |
| Si |
Silt |
Si |
| St |
Stones |
St |
| G |
Gravel |
G |
| P |
Pebbles |
P |
| Cb |
Cobbles |
Cb |
| Rk; rky |
Rock; Rocky |
Rk |
| Co |
Coral and Coralline algae |
Co |
| Sh |
Shells |
Sh |
| S/M |
Two layers (shown here: sand over mud) |
S/M |
| Wd |
Weed (including Kelp) |
Wd |
 |
Kelp, Seaweed |
 |
 |
Mobile bottom (sand waves) |
 |
 |
Freshwater springs in seabed |
 |
 |
Area with stones, gravel or shingle |
 |
 |
Rocky area, which covers and uncovers |
 |
 |
Coral reef, which covers and uncovers |
 |