The Bay is approximately 200 miles long from its northern headwaters in the Susquehanna River to its outlet in the Atlantic Ocean. It is 2.8 miles wide at its narrowest (between Kent County's Plum Point near Newtown in the east and the Harford County western shore near Romney Creek) and 30 miles at its widest (just south of the mouth of the Potomac River which divides Maryland from Virginia). Total shoreline including tributaries is 11,684 miles, circumnavigating a surface area of 4,479 square miles. Average depth is 21 feet, reaching a maximum of 174 feet. The Bay is spanned twice, in Maryland by the Chesapeake Bay Bridge from Sandy Point (near Annapolis) to Kent Island and in Virginia by the Chesapeake Bay Bridge–Tunnel connecting Virginia Beach to Cape Charles.

     Known for both its beauty and bounty, the Bay has become "emptier", with fewer crabs, oysters and watermen (fishermen) since the mid-20th century. Nutrient pollution and urban runoff have been identified as major components of impaired water quality in the bay stressing ecosystems and compounding the decline of shellfish due to overharvesting. Restoration efforts that began in the 1990s have continued into the 21st century and show potential for growth of the native oyster population. The health of the Chesapeake Bay improved in 2015, marking three years of gains over a four-year period, according to a 2016 report by the University of Maryland. The bay is experiencing other environmental concerns, including climate change which is causing sea level rise that erodes coastal areas and infrastructure and changes to the marine ecosystem. These changes have already changed the coastline eroding islands like Holland Island or Long Island and threatening local infrastructure and economies.

       (from Wikipedia)