Please note that all charts are folded in half for storage and handling. This is the marine industries standard.
If you require an unfolded copy (ie: flat for framing), please make note of this in the comments at checkout.
This official Nautical Chart is produced by the Australian Hydrographic Office, and corrected fortnightly to 'Notice to Marines' by Cairns Charts & Maps. This ensures it remains compliance with Safety of Navigation requirements. This marine chart, or 'sea map', is primarily produced to support the safe navigation of commerical shipping through Australian, Papua New Guinea and Somolon Island waters.
Nautical charts depict the seabed, or bathymetry, using a variety of colours to shade the depth regions. Darker blues indicate shallower water, while light blues and white indicate deeper water. A chart will also show continous contour lines (at varying intervals dependingo the scale of the chart), 'spot depths' across the whole area, as well as different symbols indicating wrecks, shallow rocks and dangers, as well as details on lights, light houses, tides and currents.
For extensive detail on the symbology of nautical charts, the Symbols and Abbreviations used on Admiralty Charts is the definative reference.