Photos of the Long Island Sound

About the Sound

Long Island Sound –
By the Numbers

  • Area of the Long Island Sound 1,320 square miles
  • Area of the drainage basin or watershed 16,820 square miles
  • Average Depth 63 feet (60-120 feet)
  • Water Volume 18 trillion gallons
  • Length of Coastline 600 miles
  • Salinity range at the western end 23 parts per thousand
  • Salinity range at the eastern end 35 parts per thousand
  • % of fresh water that comes from three major rivers 90%
  • Avg. winter and summer water temperatures (2011) 37°F winter/69°F summer
  • No. of tides each day (greatest tides in the west) 4 tides (2 high, 2 low)
  • Population living within 50 miles more than 23 million people
  • Estimated value to the local economy per year $9.4 billion  (2015 dollars)
  • No. of finfish species found in the Sound More than 120 finfish species
  • No. of tropical species that stray here seasonally 21 tropical species
  • No. of species that spawn in the Sound at least 50 species

Sound Facts


It’s long, narrow and shallow

Long Island Sound is an estuary, a place where fresh and salt water mix. It gets salt water from the Atlantic Ocean and 90% of its freshwater from three major rivers: the Thames, the Housatonic and the Connecticut.
Learn more about this fact
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