The River Stinchar rises in the Carrick Forest, approximately one kilometre from the source of the River Girvan, and flows south-west for a main drainage course of 54 kilometres, passing through Barr, Pinwherry, and Colmonell before entering the sea at Ballantrae on the Ayrshire coast. The catchment covers 314 square kilometres and includes the main tributaries of the Muck Water, the Duisk River, the Water of Assel, and the Water of Tig. The Action for Access database lists 41 kilometres of the river.

The valley character is relatively low-lying along the main stem, with tributaries draining steeper valley sides. Land use in the catchment is dominated by forestry, hill grazing, and agriculture, with a low human population density and very little industry, giving the river a largely rural setting.

Water quality on the Stinchar is generally very good, with a diverse range of invertebrates present even in the lower reaches. The river supports salmon, trout, eels, minnows, sticklebacks, and both sea and brook lampreys. The Stinchar is particularly noted as a stronghold for eels, with a widespread and abundant population throughout the catchment.

The river has a long-standing reputation as a salmon fishery, especially for its autumn run, which historically produced notably large fish. Anglers are active on the river, and paddlers should be aware of fishing activity, particularly during the salmon season. The Stinchar District Salmon Fishery Board maintains a presence on the river, and paddlers planning trips should consider potential interactions with fishing operations, especially in autumn when the salmon run is at its peak.