Opal lake – Crystal Lake and Siberia

Opal lake – Crystal Lake and Siberia

Opal lake – Crystal Lake and Siberia

Opal Lake, situated between high steep cliffs and immediately next to Hammer Lake, is a relic from a time when granite quarrying was a major source of income and employment on Bornholm. Opal Lake, Crystal Lake and Siberia are among the oldest quarries on the island.

Before the Opal lake was formed, the area was a large rocky outcrop of grass. In 1872, Bornholm was also hit by a storm surge, destroying the harbours. As compensation for the losses, Allinge-Sandvig was given Hammerknuden by the State. The idea was for the municipality to rent out grazing land to farmers’ cattle and thus generate income. But the municipality sold the area to a German merchant Martens for 16,000 rdl. The money was used to repair Allinge harbour.

Grandfather Martens now began to quarry granite. In 1891, however, he sold Hammerknuden to his brother-in-law, the merchant H. Ohlendorff. Together with C. F: Tiegten Bornholms Granitværk was started.

When granite quarrying started, people started blasting, with black powder, the granite away from the top of the rock and then working their way down through the rock. The granite was broken into floors of 22 m each. So how deep the hole really is, it has not been possible to find an answer, but since at Opalsøen is offered the possibility of rapelling, it is said that it takes place at a height of 43 m, then add the lake’s depth, which is about 10 m and the distance from the edge to the water level, together it may give a total depth of the break of 70 about 70 m. When granite quarrying ceased in the area in 1971, the hole was left to nature and the quarry slowly filled with water.

There is a story that when they stopped mining the opal lake, they left a large excavator at the bottom of the quarry because it was generally no longer worth anything and the water had already started to seep in. This machine should apparently still be in the break. However, the story is not yet confirmed or denied.

Like Lake Hammer, Lake Opal is also used as an ice rink. There are lots of activities in the summer – rappelling, climbing, jumping, a cable car where you end up in the cold water of the lake and many other physical activities.

If you’re not into that sort of thing, there’s a good trail system that goes around the whole of Hammerknuden, where you can see the several remains of quarrying, the Hammer Lighthouse and Solomon’s Chapel. A large part of Hammerknuden is fenced as many sheep go and maintain the area. Gates in the fence allow people to get in and out of the enclosure.

The cliff sides are used by a number of birds for their nesting sites. In recent years, a few peregrine falcons have settled on these rocks, during the breeding season the area is closed off to give the birds peace.

Crystal Lake

Crystal Lake is another of the former quarries, it is located above Opal Lake. This breach is not that big or deep. Here the breaking was done by hand. Holes were made using a drill and two men with large hammers. The hole was filled with black powder, the fuse ignited, and then it was blown up. The hole is today a beautiful lake that has been filled with rainwater over time.


Siberia is the third of the quarries and is located at the top of the cliff, close to the old pond. This was the worst place the stonemasons could work. Here, the work was also done by hand, but as the quarry is completely open in the landscape, it was always windy. In autumn and winter, the biting cold went through the marrow and bones, hence the name of this breach, Siberia. This small break is also today a nice little lake that has been filled with rainwater over time. Today, the area is also a place to avoid in autumn and winter, precisely because of the cold.

Try a ropeway at Lake Opal

Opal Lake is more than just an old granite quarry, the lake is now used for one of Denmark’s longest rope courses and certainly Bornholm’s longest and perhaps also the most fun. The ropeway offers a ride of 290 metres and starts about 50 metres up in the rocks. So if you hear screams while you’re at the opal lake, it’s not necessarily something wrong, just people having fun on the long way down.

On the 290 meters you can reach speeds of up to 70 km/h and when you hit the water your average speed is about 40 km/h.

It is strongly recommended that you put on a swimsuit before taking your first ride on the cable car, as you are sure to hit the water. You will be provided with harnesses fitted with pulleys for each rope, to provide high safety.

The rope has a breaking strength of over 5000 kg and is at no time tensioned to the maximum.

Be prepared for a walk of about 8 minutes before you can get down the cable car again, but it’s worth the trip!

Practical info

A ride on the cable car costs DKK 189 and subsequent rides cost DKK 95. If you lose your money after you have reached the top, it is possible to get your money back. The ropeway can be tested daily from 10:00 – 17:00 from approx. 30 June to 12 August.

Read more at Tovbanen.dk