Gronligrotta

Gronligrotta lies in the limestone and marble belt around Mo i Rana, an area riddled with some two hundred caves formed as water from the Svartisen glacier worked down through the soluble rock. It has been open to visitors since 1914 and is the only lit show cave in Scandinavia, with electric lighting along a guided route of about twenty minutes through chambers, passages and a section beside an underground river, including a granite block wedged in the passage and a stretch where the roof lowers. The temperature holds around six degrees year-round. The neighbouring Setergrotta offers a rougher alternative: a two-hour caving trip with overalls, helmet and lamp through unlit passages, crawls and squeezes.

What you actually see

• The lit passages - the only electrically lit show cave in Scandinavia.
• The underground river - water running through the lower chambers.
• The wedged granite block - a boulder jammed in the passage roof.
• Setergrotta nearby - an unlit caving trip for those wanting more.

When to go

June to August, which is the operating season for tours; the caves close outside summer. The temperature inside is constant, so warm clothing is needed even in July.

Honest expectations

The tour is short, around twenty to thirty minutes underground, and runs at set times in groups. The passage is wet, uneven and low in places, unsuitable for wheelchairs and awkward for tall visitors. Photography is limited by the low light.

Nearby

Marmorslottet is a short drive along the river; Svartisen and Mo i Rana lie either side.