Molesworth, 130km southwest of Blenheim is New Zealand's largest farm. Located between the Spencer Mountains and the Kaikoura ranges, Molesworth covers 180,000 hectares and is able to support over 10,000 head of cattle. First discovered as a result of the need for a stock route to Canterbury, Molesworth originally consisted of four separate runs which had mismanaged, and were surrendered to the Crown between 1938-1949. Overstocking, repeated burning, and plagues of rabbits all contributed to massive erosion. New management techniques were introduced, burning was ended, and mixed sheep-cattle farming replaced sheep alone. As a result of these changes, Molesworth is now self sufficient, and both a conservation and farming success. The climate is difficult, with a short growing season, and frosts 255 days of the year. Rainfall varies from 668mm in the east to 1800mm in the west. Temperature ranges from 30 degrees Celsius in summer to a low of -10. Snowfalls of 100mm occur in winter.
Vegetation consists of tall grasslands and beech forest. In Jollies Pass scenic reserve, subalpine scrub is common. Large numbers of bird species frequent Lake Tennyson and the Tarndale lakes. Brown trout and salmon are found in the rivers. Historic buildings include Cob cottage built in 1865 by John Murphy, Acheron cob Accommodation House built in 1863 as a resting place for stockmen and travelers between Nelson and Canterbury.