Yanartaş , Turkish for "flaming stone") is a geographical feature near the Olympos valley and national park in Antalya Province in southwestern Turkey. It is the site of dozens of small fires which burn constantly from vents in the rocks on the side of the mountain. Directly below the fires are the ruins of the temple of Hephaistos, the Greek god who was associated with fire through his role as the blacksmith to the gods. To see the fires and the ruins, visitors must first go to the entrance at the foot of the mountain. The site is at the top of a one kilometre climb. This is basically a rock stairway and is easily managed. Most people visit at night, when the fires are at their most spectacular.
In ancient times sailors could navigate by the flames, but today they are more often used to brew tea.
It has been suggested that the fires are the inspiration for the fire-breathing Chimera in Homer's Illiad.
The site was identified as the ancient Mount Chimaera by Sir Francis Beaufort in 1811, and described by T. A. B. Spratt in his Travels in Lycia, Milyas, and the Cibyratis, in company with the late Rev. E. T. Daniell. The discussion on the connection between the myth and the exact location of Chimera was started by Forbiger in 1844. The English archaeologist George E. Bean was of the opinion that the name was "allochthonous", meaning that it had originated somewhere else. He believed that the original location was further west, as cited by Strabo, at a location where similar fires burned.
The location is 80 km southwest of Antalya, near the town of Çıralı. The area is located on a track popular with hikers and trekkers on the Lycian Way.
The fires are grouped over an area of 5000 m2 and are fueled by gas emissions which have been burning for at least 2500 years. These emissions seem to change seasonally: vents and flames are more vigorous in winter months. This is a common characteristic of such seeps, where gas flux is typically modulated by gas pressure build-up induced by groundwater recharge and changes in atmospheric pressure.