The principal feature f concern to boaters is the depth. For any system of depth information, there must be a depth plane or datum. Depth information is shown on a chart by many small printed figures. These indicate the depth at that point, usually measured in feet or fathoms. This information is especially valuable when you are anchoring, so take advantage of it wherever it appears.
Examples are piers, bridges, overhead power cables, and breakwaters.
Locations of prominent isolated objects, tanks, stacks, spires, etc. are shown accurately so they may be used for taking bearings. Symbols and Abbreviations Simple inspection of many symbols will reveal a pattern in the way they are formed. Of you know the general principles of chart symbols, you'll have an easier time learning the details. Buoys, except mooring buoys, are shown by a diamond-shaped symbol and a small open circle indicating the position. Other buoys are shown by open outline symbols with the color indicated by an appropriate abbreviation.