Caves of Finland

Caves in a country that shouldn't have any

Finland's bedrock is granite and gneiss, hard and insoluble. It doesn't form caves the way limestone does, dissolving under water into kilometres of stalactite passages. And yet Finland has hundreds of caves. They are smaller, darker and often harder to find, and that's exactly what makes them interesting: each one has a reason to exist.

Four ways to form

Boulder caves are the most common. The ice age piled large boulders at the foot of cliffs or on slopes, and hollows were left between them. The Luolavuori cave system in Turku and the Rapala caves in Kangasniemi are of this kind; at Rapala, villagers hid there during the Great Wrath.

Crevice caves are cracks in the bedrock, widened by the ice sheet and frost. Brannin luola in Loviisa and many a "pirunpesä" (devil's nest) belong to this group.

Limestone caves are rare, since limestone occurs only in narrow bands around Lohja, Parainen and parts of Lapland. Torhola in Lohja is the country's largest: 31 metres long, with small stalactites on the ceiling.

Weathering caves predate the ice age. Susiluola in Karijoki formed at the boundary of sandstone and granite, long before the last glaciation. Stone tools found there have been dated to over 120,000 years old – if that reading holds, they are traces of Neanderthals and the oldest sign of humans in the Nordic countries.

Ice caves and other curiosities

On an island called Korkia-Maura in Lake Inari is a cave where ice lasts beyond summer. It was used as a fish cellar as far back as the 1600s, and it's the largest of its kind in Finland. Climate warming has thinned the ice in the 2000s. Inside Pirunvuori in Sastamala are caves, and at the top a stone castle built by a painter. Valtari climbing cave in Kouvola is a training spot for climbers.

Before you go

• Always bring a headlamp, even for a short cave. A helmet or cap too: the ceiling is low and sharp.
• Caves are wet and around 4°C even in July. Wear shoes with good grip and dress in layers.
• Don't go deep alone. Tell someone where you're going and when you'll be back. Phones don't work inside rock.
• Some caves are bat hibernation sites. Don't visit between October and April; waking a bat from hibernation can kill it.
• Susiluola is closed. At the Rapala caves, the steps and signs have been removed, and visiting is at your own risk.