The Liffey (Irish: An Life) is the river which flows through the centre of Dublin.  It is 125 km (75 miles) long. 

The river was previously named An Ruirthech, meaning “Fast or Strong Runner”.  The word Liphe (or Life) referred originally to the name of the plain through which the river ran, but eventually came to refer to the river itself.

Origin – Mt. Kippure, County Wicklow
Mouth – Irish Sea at Dublin Bay