Grottes de Koumac

Useful Information

Location:	Koumac, North Province, Grand Terre Island. RT1 at roundabout in Koumac take Avenue Georges Badoux to the northeast which soon becomes Route des Grottes de Koumac. Follow to the end. (-20.5353568, 164.3398168)
Open:	All year daily 6:30-18. [2026]
Fee:	free. [2026]
Classification:	Karst Cave
Light:	bring torch
Dimension:
Guided tours:	self guided
Photography:	allowed
Accessibility:	no
Bibliography:
Address:	Grottes de Koumac, Route des Grottes de Koumac, Koumac, North Province, New Caledonia, 98850, France
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History

Description

The Grottes de Koumac (Koumac Caves) ar named after nearby town Koumac, they are located 8 km east in the forested limestone hills of the same name. The massif of Koumac covers some 20 km², the highest peak reaches 374 m asl. The limestone ist kastified and riddled with cave, the surface shows typical karren and stone forests. At the end of the road there is a free camping site and the trailhead for the access to the caves. The plural in Koumac Caves is justified, as there are two caves accessible to the public. While there are generally no restriction, the visit during the night is not allowed, probably to reduce vandalism. People tend to light fires in caves at night. If you visit the cave at your own you need a rental car, as there is no bus access. There are also guided tours of the area which include the visit of the caves, it is probably best to ask at your hotel desk for such tours.

The Petite Grotte des Vents (Little Cave of the Winds) is a rather small cave, which is mostly a narrow and high passage. The visit takes about 20 minutes. A torch is helpful but not required, as the cave is rather small and mostly lit by daylight.

Much bigger is the Grande Grotte (Big Cave) which is accessible for 380 m, and the visit takes about an hour. This cave is more demanding, it is necessary to climb up a hill over huge boulders to reach the entrance. Also, it is not allowed to enter the cave during wet weather, when the cave might become quite dangerous because it frequently floods. And there are actually several rules for entering the cave. There is a cahier d'émargement (sign-in book) at the parking lot were visitors must fill in the required details before entering the main cave. The accessible part ends after 380 m with a cave lake. While it is possible to continue, it is strictly forbidden, and actually quite dangerous as some parts of the cave at about 2 km from the entrance contain carbon dioxide in high amounts which might be deadly. The other rules are basic safety rules for semi-wild caves: wear comfortable walking shoes, bring at least two lamps per person, never cave alone, and bring water. We would add sun protection and insect repellant.

The caves were known to the natives for a long time, and were used as burial caves. The scientific exploration and surveying happened in the 70s and 80s. The limestone was formed during the Eocene, between 53 and 34 Ma BP. They were uplifted and karstification started.

Both caves have a narrow gorge-like character, the bigger one has some fine speleothems. Pleas do not touch the speleothems, the salt, sweat and other things on your skin damages them. While the cave itself is not that spectacular, the gorge like entrance section with trees growing out of the gorge is quite impressive.