Near Narlıkuyu, a road winds north for 1.5km to several caves – sinkholes carved out by a subterranean river and places of great mythological significance. The walk from Narlıkuyu junction to the main entrance gate is quite steep. Enterprising locals usually offer taxi services up the hill for ₺5 (one way).
The mammoth underground Chasm of Heaven (Cennet Mağarası) – 200m long, 90m wide and 70m deep – is reached by 450-odd steps to the left of the ticket booth. Right in front of the cave mouth are the tiny but beautiful remains of the 5th-century Byzantine Chapel of the Virgin Mary, used for a short time in the 19th century as a mosque. Once inside the cave, the stairs can be very wet and slippery and there are no handrails, so wear decent shoes and walk carefully. At the furthest end of the colossal grotto is the Cave of Typhon (Tayfun Mağarası), a damp, jagged-edged, devilish theatre. Locals believe this to be a gateway to the eternal furnace and Strabo mentions it in his Geography. According to legend, the cave's underground river connects with the hellish River Styx – this seems plausible when you hear the underground current thundering away below.
Follow the path from the ticket office further up the hill to the Gorge of Hell (Cehennem Mağarası) with its almost vertical walls that you view by stepping out onto a heart-stopping platform extending over the 120m-deep pit. This charred hole is supposedly where Zeus imprisoned the 100-headed, fire-breathing monster Typhon after defeating him in battle.
Around 600m west of the main entrance is the Asthma Cave (Astim Mağarası), which supposedly relieves sufferers of the affliction. It's worth the extra ₺5 to explore these other-worldly grottoes, with their staggering limestone formations.