Sitting atop of Double Island Point is an unmanned lighthouse that flashes every 7.5 seconds. Named by Captain James Cook in 1770, Double Island Point is volcanic extrusion that has dammed the sand in the north flowing longshore drift to form a massive triangular sand mass that ties the outcrop to the mainland.
This sand mass is known as Cooloola. It includes a complex of high dunes and swales.
The sand mass acts as a great soak for rainwater and this ground water is evident as swamps and lakes where groundwater level rises above the bottoms of the swales.
Around the perimeter of the sandmass, both on the inland side as well as on the ocean shore, freshwater flows from this sand mass. Lake Cooloola and the saturated riverine plain of the Noosa River upstream of Lake Cootharaba are fed by this water system.