Follow the signs from Baunei up a 2km climb of impossibly steep switchbacks to the plateau. Head north following the Su Sterru (Il Golgo) sign for less than 1km, then leave your vehicle and walk over to this remarkable feat of nature – a 270m abyss just 40m wide at its base. Its funnel-like opening is now fenced off but, knowing the size of the drop, just peering into the dark opening is enough to bring on the vertigo.