The Kalgan River flows 140 kilometres through steep hillsides of lush forest and rolling farmland near Albany, Western Australia, before reaching Oyster Harbour and ultimately Frenchman Bay. The lower reaches are tidal and open into a broad expanse of water, while the upper sections narrow and become increasingly sheltered by tall shady trees. The river's water has a notably dark, ink-like quality. The established paddle trail runs 10 kilometres one way between the Lower Kalgan Bridge and the Wheeldon Road Bridge, rated Grade S01 — a flat water route with no portage, suitable for all types of paddle craft and paddlers of all abilities. The trip typically takes two to two and a half hours one way.

The recommended launch point is on the west side of the river at Lower Kalgan Bridge, approximately 15 kilometres from Albany Town Square via York Street, Lockyer Avenue, Ulster Road, Lower King Road, and Nanarup Road. A car park sits on the north side of the road just before the bridge. Additional launch sites are available along the 2WD-accessible road on the east bank of the southern half of the route, including at the start of the Luke Pen Walk on the east bank. The Kalgan River Chalets and Caravan Park, located on the west bank around the first bend upstream, also provides river access.

Tidal influence is significant in the lower reaches, and paddlers should plan their trip accordingly — paddling upstream against an outgoing tide means the return journey will be assisted by the flow. At low tide, channel markers help identify deeper water. The river carries a moderate level of motorboat traffic, and a designated water ski area is managed by the Albany Water Ski Club roughly 3 kilometres upstream from the Lower Kalgan Bridge. Paddlers are advised to stay close to the bank where possible.

Notable points along the route include the Water Ski Club facilities at approximately 4 kilometres and Elbow Island at around 4.5 kilometres, which is worth circumnavigating. Wildlife commonly observed includes pelicans, ducks, osprey, cormorants, thornbills, splendid and red-capped fairy wrens, grey currawong, and western yellow robin. The river is also known as productive fishing grounds for bream and mulloway. The trail is accessible year-round, with July through September noted as a good period for wildflowers along the banks.