The River Colne is a tributary of the River Thames in southern England, flowing approximately 58 kilometres (36 miles) through Hertfordshire, Buckinghamshire, Greater London, and Surrey. Its source lies near Brookmans Park in Hertfordshire, and it meets the Thames at Staines. No paddling licence is required to paddle the river.

The Colne Valley provides a mix of natural and historical features along its length. Between Rickmansworth in the north and Denham in the south, the river meanders alongside and through a series of lakes, running parallel to the Grand Union Canal. This section is particularly accessible for paddlers, with the Rickmansworth Aquadrome serving as a well-known put-in point with a large car park. Paddlers can connect to the river from the Aquadrome via the Grand Union Canal, joining the Colne near the Frogmore Wharf area by the Tesco store.

Paddlers should be aware of weirs along the course, which require care and can present capsize risk. Overhanging trees and sections where vegetation nearly blocks the river are also noted hazards, particularly in shallower stretches. The river has documented water quality and litter issues; clean-up efforts have repeatedly recovered significant quantities of plastic, glass, cans, and other debris, suggesting ongoing pollution concerns that paddlers should be aware of.

The river is suitable for both novice and more experienced paddlers. Kayaks are well-suited to navigating shallower, tree-lined sections, while open canoes can manage the broader stretches. A popular route involves paddling from the Rickmansworth Aquadrome along the Grand Union Canal and then onto the Colne itself. The Action for Access database lists several distinct sections of the river, including a 17-kilometre stretch around Rickmansworth and upstream, a 2-kilometre section from Batchworth to Springwell, and a 28-kilometre section from Maple Cross to Staines.