The Rivière Jupiter is the most significant river on Anticosti Island, located in the Minganie Regional County Municipality on Quebec's North Shore. The river runs approximately 82 kilometres (alternatively cited as 79 km) from its headwaters at Létourneau Lake, situated 189 metres above sea level near the centre of the island, before emptying into the Gulf of Saint Lawrence. The watershed covers roughly 970 square kilometres and is fed by ten tributaries.

The river's character changes considerably along its course. Flow is moderate in the upper reaches and becomes rapid downstream, where the river cuts through a dramatic canyon with walls reaching up to 100 metres in height. This canyon section represents one of the most visually striking features of the route. The surrounding landscape supports large populations of white-tailed deer and seals are visible along the shores near the river's mouth.

The river is managed by Sépaq Anticosti, which organizes guided canoe trips down the Jupiter as part of hunting packages in August and September. During these trips, participants travel through the river's pristine waters, and early-season guests may also fish for Atlantic salmon, for which the Jupiter is particularly well known. The river is described as the premier salmon river on Anticosti Island, and sport fishing is a primary draw for visitors.

Access to Anticosti Island itself is only possible by boat or plane, as there are no road connections to the mainland. The nearest community is Port-Menier, located approximately 112 kilometres west of the river's source. Sépaq Anticosti manages accommodations and logistics on the island, including cabins in the Jupiter sector near the river's mouth. Inquiries and bookings can be directed to Sépaq Anticosti at 1-800-463-0863 or anticosti@sepaq.com.

Given the remote island location, self-supported paddling on the Jupiter requires careful logistical planning. The combination of rapid downstream sections, a deep canyon, and the island's isolation make this a serious undertaking. Paddlers should be aware that the river operates within a managed territory where hunting and fishing regulations apply, and coordination with Sépaq Anticosti is advisable before planning any trip.