To solve the volume of water in units of cubic meters, we are going to convert first all units in terms of meter.
Let us say that the dimensions are:
length l = 4.40 nautical miles
width w = 3.90 nautical miles
depth h = 20 fathoms
Converting the dimensions to meters:
l = 4.40 nautical miles (6076 feet / nautical mile) (1 meter / 3.28 feet) = 8,150.73 m
w = 3.90 nautical miles (6076 feet / nautical mile) (1 meter / 3.28 feet) = 7,224.51 m
h = 20 fathoms (6 feet / fathom) (1 meter / 3.28 feet) = 36.59 m
The volume of a rectangular prism is:
V = l w h
Substituting the values:
V = (8,150.73 m) (7,224.51 m) (36.59 m)
V= 2,154,330,380 cubic meters