In view of the ever-changing limits of the Sound, quoted numbers for 
volume, surface area, mean depth, miles of shoreline and number of islands 
mean little unless the boundaries are carefully and accurately specified. 
Hereafter, any reference to Puget Sound in this paper means that body of 
water bounded at Deception Pass and the north end of Admiralty Inlet. If 
a greater region is to be referred to, then descriptors such as Puget 
Sound and adjacent waters, the greater Puget Sound region, or specific 
names for adjacent areas will be used. 
Puget Sound proper has a shoreline length of 1,157 nautical miles. Its 
surface area at mean high water is 767.6 sq. nautical miles. It contains 
a volume of 26.5 cu. nautical miles at mean high water and gains and loses 
a mean intertidal volume of 1.27 cu. nautical miles each change of the 
tide (McLelIan, 1954). These numbers give the initial clues to why Puget 
Sound is unique among all estuarine systems in the continental United 
States and why Puget Sound responds in its own way to both natural and 
anthropogenic stress. 
The volume and surface area can be used to determine the mean depth of the 
Sound, 210 ft. This depth takes into consideration all the small, 
shallow, appended inlets as well as the deeper main channels. Table 1. 
If the mean depth of the main basin alone is calculated it is found to be 
329 ft. Main basin depths range from 0 to 930 ft. maximum with typical 
midchannel depths of 600-800 ft. The small appended inlets attached to 
the main channels have mean depths that are in tens of feet, e.g. 12.0 ft. 
for Eld Inlet. 
Table 1 
Area, Volume Table for Puget Sound 
Region 
Area MHW 
2 
n. mile 
Volume MHW 
• 1 3 
n. mile 
Mean Di 
ft. 
South Sound 
130.7 
2.49 
116 
Main Basin 
223.5 
12.1 
329 
Hood Canal 
113.2 
3.92 
210 
Whidbey Basin 
184.9 
4.58 
150 
Admiralty Inlet 
115.3 
3.41 
179 
Total Sound 
767.6 
26.5 
210 
Source--McLellan, 1954 
These values point out that for Puget Sound in general over half of the 
volume of water lies below the photic zone judged to be effective to 
about 100 ft. depth. In the main basin about 80 percent of the water 
volume is below the photic zone, whereas nearly all the water in the 
3 
