Mount Parnassus stands in Central Greece, north of the Gulf of Corinth. Its highest peak is Liakoura, at 2,457 metres. The mountain spreads over three regional units, Phocis, Boeotia and Phthiotis, and most of it is in Phocis. A high pass joins it to Mount Giona in the north-west. On the eastern side is the valley of the Kifissos river of Boeotia, and on the western side is the valley of the town of Amfissa.

The core of the mountain is limestone, with high cliffs and many caves. Closed basins in the middle of the mountain divide it into two parts. The western part is lower and covered with forest. The eastern part has the high peaks, among them Liakoura and Gerontovrachos. Between them lies the plateau of Livadi, above the town of Arachova. Bauxite has been mined on the slopes since the 1930s.

In winter, people come to Parnassus for skiing. The Parnassos Ski Centre was built in 1975 and 1976 and has two bases, Kellaria and Fterolakka, joined by a lift. Its runs lie between 1,640 and 2,260 metres. There are more than twenty runs and seventeen lifts, and four of the runs are approved for international races. Ski schools and shops that rent equipment work at both bases.

In the other seasons the mountain is for walking. A marked path climbs from Kellaria to the peak of Liakoura in about three hours, over open rocky ground, and it suits experienced walkers. The European path E4 crosses the western part of the mountain. One old section of it, the path of Pausanias, goes down from the Corycian Cave to Delphi in about three hours. On the plateau of Livadi, local companies take visitors mountain biking and horse riding.

For the ancient Greeks, Parnassus was the mountain of the god Apollo and of the Muses. In one myth, the boat of Deucalion came to rest on its peak after the great flood. The sanctuary of Apollo at Delphi stands on the south-western slopes.

Higher up, at about 1,360 metres, is the Corycian Cave, which was sacred to the god Pan and to the nymphs. Its first chamber is about 90 metres long, 60 metres wide and 50 metres high. French archaeologists dug here around 1970 and found thousands of small offerings, most of them animal knucklebones that people used as dice. People of the area hid in the cave during the Persian invasion in the 5th century BC. The cave is open and free to enter.

The Parnassos National Park was created in 1938, in the same year as the park of Mount Olympus. It covers about 36 square kilometres between Delphi, the town of Arachova and the village of Agoriani. Most of it is a forest of Greek fir, which grows up to about 1,800 metres. Black pines grow on the north-eastern slopes. Above the trees the ground is open, with grass and rock.

A wild flower, the Parnassus peony, has been found only on this mountain. Foxes, badgers, wild boar and wolves live in the forest, and birds of prey and woodpeckers are seen there. The western part of the park is gentler and forested, and the eastern part has the steep peaks.