The Mersey River rises on the Central Plateau of Tasmania south of Lake Rowallan and flows north to enter Bass Strait at Devonport, in the state's northwest. The river is fed in part by water releases from the Rowallan Power Station, which influences flow conditions at the whitewater section located within the Mersey White Water Regional Reserve. This site has a history as a former host of the National Slalom Championships and is regarded as a popular destination for both locals and visitors seeking challenging whitewater kayaking and rafting.

The whitewater section is described as offering challenging conditions, making it more suitable for paddlers with developed skills. The Parks and Wildlife Service Tasmania directs paddlers to consult Paddle About Tasmania for information on difficulty gradings and complexities specific to Tasmanian whitewater rivers, and recommends reviewing safety information from Paddle Australia and Marine and Safety Tasmania before launching.

Beyond the whitewater reserve, the river corridor spans a significant length through varied terrain. The Inland Fisheries Service references a 55-kilometre stretch from Lake Parangana to Latrobe, with access points at locations including Mersey Forest Road, Olivers Road, Liena, Union Bridge, Dynans Bridge, Kimberley, Merseylea, the Warrawee Conservation Area, and Latrobe. The river bed through much of this stretch is covered with slippery, round rocks, which presents a wading hazard and is worth noting for paddlers who may need to portage or wade in shallower sections.

Tasmania's rivers have a general reputation for clean, high-quality water, consistent with the island's broader environmental character. The Mersey passes through forested and rural landscapes on its way from the Central Plateau to the coast, offering a range of paddling environments from the upper whitewater reaches to calmer lower sections near Latrobe and Devonport.

The river is managed as a wild trout fishery, and separate whitebait fishing regulations also apply. Paddlers sharing the water with anglers should be aware of this activity, particularly in the more accessible lower sections where fishing pressure may be higher.