Atlantic seaboard watershed

The continental area east of the Appalachian Mountains and highlands to the north and south is demarcated on the south by drainage to the Lake Okeechobee basin (which drains both westward to the Gulf and eastward to ocean), the Eastern Continental Divide (ECD) to the west, and the Saint Lawrence divide to the north. US physiographic regions of this watershed are the Atlantic Plain and the Appalachian Mountains & Highlands.

Sub-watersheds adjacent to the Saint Lawrence divide

• Chedabucto Bay: 2,148 square miles (5,560 km²)
• Gulf of Maine: 69,115 square miles (179,010 km²)
• Long Island Sound: 16,246 square miles (42,080 km²)
• Lower New York Bay: >14,000 square miles (36,000 km²)

Other notable sub-watersheds

• Delaware Bay: 14,119 square miles (36,570 km²) — larger than several, but not adjacent to either divide

Rehoboth Bay

Indian River Bay

Assawoman Bay

Isle of Wight Bay

Sinepuxent Bay

Chincoteague Bay

• Chesapeake Bay: 64,299 square miles (166,530 km²) — adjacent to both divides (at the Triple Divide point)

Sub-watersheds adjacent to the Eastern Continental Divide

• Albemarle Sound: >14,380 square miles (37,200 km²)
• Winyah Bay: >7,221 square miles (18,700 km²)
• Santee River: >4,531 square miles (11,740 km²)
• Savannah River: 9,850 square miles (25,500 km²)
• St. Johns River: 8,840 square miles (22,900 km²)
• Biscayne Bay: >2,800 square miles (7,300 km²)
• Kissimmee River: 3,000 square miles (7,800 km²)