When diving on the west side of the Nessoden peninsula in Søndre Spro or even ProDykk, its worth making a short stop at the Spro Gruve which is only couple of minutes drive from both locations. It can be accessed from the coastal walk between Fjellstrand and Fagerstand, or just by parking nearby in the Nordre Spro. The Spro Cave is actually a former stone mine that finished its operations at the end of WWI. The main entrance leads you through a tunnel about 30m into the mountain where it opens into a big hall. The roof has collapsed, creating a big opening in the main hall, with huge rocks pilled up in middle. The opening lets in plenty of light and you can see trees growing at the edges of the hole. The walls and paths are glittery with sheets of muscovite rock (or Crow's silver as Norwegians call it) making the place really special. The cavern has also a small pool. Inside the mine the air is much cooler and humid then outside enhancing the feel of of a cave. Behind the mound of rocks you can find the northern tunnel that will lead you back to the shore through a tighter squeeze through rocks. Outside, the shore offers many nice areas for picnic or camping underneath pine trees.
Inside the Spro Gruve
Holes in the collapsed ceiling of the mine let in plenty of sunlight and give the place a special atmosphere.
Small pool inside the cavern of the Spro mine.
Sheets of sparkly muscovit rock line the pathways and the walls not only in the mine itself but also on the beach outside.
Exit from the northern tunnel is smaller and requires a bit of a squeeze.