The South Esk River is the longest river in Tasmania, stretching approximately 252 kilometres from its source near the Ben Lomond plateau on the Mathinna Plains at an elevation of 810 metres down to Launceston, where it meets the North Esk River at Trevallyn to form the kanamaluka/Tamar River. The river's course arcs around the southern side of Ben Lomond, passing through Fingal, Avoca, and Evandale before winding northwest through Perth, Longford, and Hadspen, ultimately flowing through the narrows of the Cataract Gorge into Launceston.

The character of the river varies considerably along its length. The uppermost sections near Upper Esk are prone to significant log jams that require frequent portaging, making paddling there time-consuming and frustrating even at moderate water levels. At 0.87 metres on the gauge at the Upper Esk Bridge, the upper section offers mostly grade 1 or flat water with a series of easy grade 2 rapids in the final kilometre or two before the fisherman's access exit on Upper Esk Road just east of Gunns Road. The Inland Fisheries Service notes that some sections of the river may be navigated in canoes, drift boats, and inflatables, but recommends experienced paddlers only and advises observing all MAST safety requirements.

Canoe and kayak launch points in the middle and lower reaches include Clarendon (paddling upstream), the Perth Riverbank Reserve at Berryman Reserve off Old Bridge Road, the Union Street boat ramp at Longford, and Hadspen (paddling upstream). The Berryman Reserve car park closes at 6:00 pm, so paddlers should plan accordingly or park outside the entrance on Old Bridge Road. Near Perth, the river becomes shallow with rapids and riffles around the first bend upstream adjacent to Mill Road, with pools beyond that section. The lower reaches near Launceston pass through the dramatic cliff scenery of Cataract Gorge before reaching the confluence with the North Esk.

Hazards noted across the river include deep water, strong currents, slippery surfaces, steep banks, falling trees and limbs, and electric fences along some stretches. A 5-knot speed limit applies within 60 metres of any shoreline, marine facility, or buoy. River flow data for the Perth and Longford sections is available from the Bureau of Meteorology. Paddling notes are also available through Paddle Tasmania at paddletasmania.canoe.org.au.