The Three Sisters


An iconic landmark in the Blue Mountains, The Three Sisters is part of the Greater Blue Mountains World Heritage Area. Towering over 900 metres high amongst the breathtaking cliffs of the Jamison Valley, this series of weathered sandstone peaks, formed over thousands of years, is a ‘must see’ for any visitor to New South Wales.


The Blue Mountains City Council presented GLG with a stringent set of criteria, the main being that any solution was to be LED based in order to provide both an energy reduction and minimise maintenance requirements. Oh, and let’s not forget it had to have the ability to project light 600m across a valley of difficult terrain.


GLG rose to the challenge of designing a solution that was robust, stable and easy to complete under dynamic conditions. A series of sample testing nights were scheduled to ensure the solution’s overall efficiency and dependability.

Installing the Tethys400 fitting with a narrow beam of 15 degrees, the benefits included a reduction in energy usage from 6000w to 1200w. By using the 15 degree beam angle, this directed a more focused beam of light, illuminating less of the surrounding bush and more of The Three Sisters themselves.

4000 Kelvin was chosen as the preferred colour temperature as the traditional 3000 Kelvin used to highlight sandstone did not showcase the finer features of the monument.

The maintenance of the lighting has always been of concern to Council, with the existing solution too hard to maintain and risky in terms of changing lamps, as this involved the need to abseil off the edge of the cliff to do so. The chosen lamps provide 50,000 hours life time, significantly reducing maintenance requirements.

Overall, not only has the look of this hugely popular tourist destination dramatically improved but the associated maintenance requirements have been improved upon.