it's called a chart. Nautical maps are referred to as "Charts".
nautical
A nautical chart (map) shows the shore and land-marks, sea bed conditions, navigation hazards, buoyed channels, and so on, relating to the safe navigation of vessels and inshore boats.
That mean the key for North, South, East, or West
usually different terrain or height above sea level
Nautical chart
Such a map is commonly known as a nautical chart.
a physical map
when a pilot use a nautical map they can see what place they are going to.
navigation on water.
water depths and navigational routes
Marine Chart or Nautical Chart.
See related link for a star map
Water depth.
according to my map, its about 3 inches
Use a chart not a map. WGS 84 is probably the best datum
it's called a chart. Nautical maps are referred to as "Charts".