The Roper Highway runs east from the Stuart Highway, 6 kilometres south of Mataranka, down the Roper River Valley, through Roper Bar and Ngukurr, ending at Numbulwar on the western side of the Gulf of Carpentaria via Numbulwar Road which is a continuation of the Roper Highway. The highway is single lane bitumen from the turn off near Mataranka for approximately 132 kilometres (40 kilometres short of Roper Bar) then it is unsealed the rest of the way and quite rough in places. The highway is flat and monotonous until you reach the end near Numbulwar where it meets the picturesque tropical Rose River. Like all rivers around the Gulf of Carpentaria it is unsuitable for swimming because of the presence of saltwater crocodiles.