Sjaunja Nature Reserve, Nature reserve in Lappland, Sweden.

Sjaunja is a 285,000-hectare nature reserve in Swedish Lapland, about 60 km north of the Arctic Circle, bounded by the Lule River to the south and the Kaitum River to the north. East of its mountain fringe, a plain of mires and lakes is dotted with rounded fells rising above the tree line; the highest point is Kårsatjåkka at 1,730 m. The reserve stretches 110 km east–west and 45 km north–south.

Sjaunja was first a bird protection area before becoming a nature reserve in 1986, the year Swedish sources give for its founding. It later joined the Laponia World Heritage Site, which unites Padjelanta, Sarek, Stora Sjöfallet, Muddus, Stubba and Tjuolda. In 2006 the company International Gold Exploration received permission to search for copper and gold west of Lake Riteljaure for three years.

The land has long been home to the Sámi people, who continue their traditional reindeer herding and fishing practices here. These ways of life shape the landscape and remain visible in how the region is used today.

The area can be reached from several entry points, with rail connections bringing visitors closer to the region. Those exploring the terrain should be prepared for changing weather and rough ground.

The area contains Sweden's largest marsh area, creating a landscape of its own character and appeal. The Kungsleden hiking trail runs through the western section, bringing hikers close to native wildlife and bird species.