The River Arun rises at St Leonards Forest [Map] being formed from a number of gills that flow through a number of reservoirs before joining to become the River Arun. It flows past Horsham [Map], Rudgwick [Map], Billingshurst [Map], is joined by the River Rother one kilometre before Pulborough [Map] after which it flows past Greatham [Map], Greatham Bridge [Map], Bury [Map], Houghton [Map], South Stoke [Map], Arundel [Map] to the English Channel at Littlehampston [Map].