The Ōpāwaho / Heathcote River flows entirely within the city boundaries of Christchurch, New Zealand, making it an accessible urban waterway for paddlers. Fed primarily by springs near Templeton Road, with its catchment extending westward to Yaldhurst and Pound Road during wet weather, the river meanders around the base of the Port Hills before flowing from west to south-east and emptying into Pegasus Bay via the Avon-Heathcote Estuary.

The river is navigable from its headwater springs — notably at Te Kuru Wetlands near Halswell and at Ngā Puna Wai near Wigram — all the way to the sea, a route that paddlers have completed as a source-to-sea trip. The Cashmere Stream joins the river near Te Kuru Wetlands, offering an alternative starting point. The lower reaches are tidal, with deep tidal channels connecting to Te Ihutai, the Avon-Heathcote Estuary. The river's sharp bends and the influence of winds coming off the Port Hills and surrounding flats are notable navigational features, particularly in the lower reaches.

Historically, the river was deep enough — six to eight metres in places — to support commercial shipping in the 1850s, when up to 15 vessels per day navigated it as far as Richardson Terrace. A towpath was established on both sides of the river where horses and bullocks towed boats upstream. Today, paddlers drifting downstream will pass through an urban landscape that retains traces of this history, including the Ferrymead area and remnants of the old steam wharf. The lower estuary section opens into a broader tidal environment with salt marsh, and connects to McCormacks Bay and Sandy Point Spit Reserve.

The river and its estuary carry significant cultural importance for Ngāi Tahu. The name Ōpāwaho — meaning "The Place of the Outward Pā" or "The Outpost" — refers to a pā sited just downstream of the present Opawa Road Bridge. The waterway was historically used as a travel and trade corridor linking Kaiapoi, Banks Peninsula, and, via a short portage near Wigram, the Halswell River and Lake Ellesmere beyond. Mahinga kai resources including tuna (eel), inanga (whitebait), pātiki (flounder), kanakana (lamprey), and waterfowl were gathered throughout the corridor.

Sediment load has been identified as a water quality concern on the river, with catchment management issues noted as a contributing factor.