The Lark Hill Dusk to Dawn is a 50km and 100km ultra marathon on an approximately 3km limestone loop course at Port Kennedy in Western Australia.
50km runners run 17 laps; 100km run 34 laps. Because the event is run at night, it is recommended that runners use a headlamp. Both events start at 7pm and there is a 13 hour cut-off, i.e. at 8am the following morning.