The Pelorus River was originally the river was known as the Hoeire by local Maori after the first canoe to travel to the South Island. The river flows east until it enters Pelorus Sound at Havelock. The valley was the site of a massacre of the Ngati Kuia and Ngati Apa by Te Rauparaha. European exploration and exploitation was begun by Lieutenant Chetwode of the HMS Pelorous in 1838, who named both the river and the sound after his vessel.
Between 1865-1866, reserves were set aside close to the site of the current bridge, and designated as areas for accommodation and the site for future towns. These settlements did not eventuate, however in the 1880s the discovery of gold in the Wakamarina, a tributary of the Pelorous led to a large population of miners in the Pelorous valley for a time. The settlement of Canvastown at the point where the Wakamarina met the Pelorus was a direct result of the mining activity. Gold was not the only resource exploited in the Pelorus Valley. Over 80km of rail track were laid through the forest to serve Brownlee's Mill. In 50 years of operation, they processed a total of 5.3 million cubic metres of timber. They ceased felling in 1915, however other smaller mills continued operation till the 1930s. Today, the site of Brownlee's Mill is marked by the wreck of a steam tug. Both the gold mining, and the milling led to extensive silting of the Pelorus River, and Pelorus Sound.
In 1903 a Scenery Protection Act was passed at the instigation of W. H. Skinner who recognised the need to preserve the environment for future generations. The remaining forest at Pelorus Bridge was finally established as a scenic reserve in 1912. A scenic board was founded by volunteers, however the reserve was under the overall control of the government. The reserve today is populated by a mixture of beech and podocarp forest. Originally the whole valley was forested in mixed podocarp swamp forest. The reserve is the habitat of one of two bat species, the only indigenous land mammals in New Zealand.
The Pelorus Bridge reserve is a popular scenic, camping and swimming area approximately mid way between Blenheim and Nelson.
In the 21st Century, the Pelorus River has been made famous by Sir Peter Jackson filming scenes for the second of The Hobbit trilogy in the Pelorus reserve area.