The River Forth has two headstreams, Duchray Water and the Avondhu, which rise on the northeast side of Ben Lomond, flowing eastward through
Stirlingshire to unite east of Aberfoyle. From there, it winds for 39 miles to
Stirling. Below that town, the river follows a tortuous course for 12 miles through a section called "The Links," which ends at Alloa in
Clackmannanshire. The
Firth of Forth, its estuary, extends 48 miles from Alloa to the
North Sea.
