Thirlmere boomed with the creation of the Great Southern Railway in 1863 to 1867, when the area was blanketed in tents to house the many railway workers that came to the area to work. Thirlmere was valued mostly for the proximity of the Thirlmere Lakes (then called Picton Lakes) which were used to provide water for the steam trains. During this period Thirlmere was also the home for a number of timber mills, whose main product was the milling of sleepers for the railway line.