The exploration of Sweden's longest flooded cave system, Dolinsjögrottan, located in the Bjurälven valley, has been ongoing since 2007. Although the entrance to Dolinsjö cave was discovered by Bo Lenander in 1979, the very high water flow in summer, making diving in the cave feasible only in winter conditions, meant that exploration of the cave only began 28 years later.

Expeditions from 2007 to 2022 allowed the discovery of over two kilometers of corridors in this longest flooded cave in Sweden and increased the total length of all caves discovered in the valley to 3353 meters.

The 2023 expedition aimed to explore two caves in the Bjurälven valley: Köldhålet and Festins, which were 223 and 65 meters long at the start of the expedition, respectively.

Characteristic of this region of Sweden is the high variability of weather conditions. During this expedition, members had to contend with temperatures around -20 degrees Celsius, but cloudless skies and sunshine somewhat brightened these short sub-Arctic days.

Due to the extremely low temperatures that occurred directly before and throughout the expedition, the river leading to Festins froze, which somewhat facilitated transportation by snowmobile. Of course, it was necessary to use a shovel and remove snow on some sections, but stable winter conditions made logistics much easier. The strong frost was, however, taxing for the expedition members: everything froze within a few seconds, and frozen diving equipment before each dive required thawing using hot water and a diesel-powered heater.

A few years earlier, the team had problems with freezing regulators. When more attention was paid to the humidity of the air drawn in by the compressor and double filtration was used, this problem was somewhat resolved. However, this year the problem returned for part of the team conducting dives in Festins cave, probably due to significantly lower temperatures in the entrance area.

Diving in Festins Cave

Upon arrival at Festins, it turned out that this year the water level was relatively low. Last year, divers put on their equipment in a pond outside, but this year it was possible to crawl inside through an uncovered cave opening.

The cave starts with a narrow corridor, descending to a depth of about 5 meters. Unfortunately, the weak water flow this year meant that visibility during the dives was very poor. The entire cave can be described as quite narrow. It is essentially a series of tight passages, interspersed with tight restrictions.

Team members installed 64 meters of guide line in a newly discovered section, which ends in a small air chamber, barely fitting one person. Due to lack of space, a decision was made to discontinue further exploration in that direction. At least for now.

Diving in Köldhålet Cave

The name Köldhålet (Cold Hole in Swedish) comes from its location: it is situated at the bottom of a very narrow and deep valley, into which the sun's rays never reach.

Access to the cave is not easy. The entrance is located 20 meters below the camp, and reaching it requires building a path zigzagging down an extremely steep slope. The equipment itself must be delivered using rope techniques.

The main passage of the cave is a flooded corridor, running from the entrance westward. From previous expeditions, it was known that halfway there is a dry chamber, from which a ten-meter-long ice slope leads to a narrow exit hole, usually blocked by ice in winter. In the further part of the flooded corridor, which takes almost an hour of diving to reach, there is an almost vertical shaft dropping from a depth of 10 meters to 20 meters. One of the expedition's goals was to create a photographic documentation of this place.

At the end of the flooded corridor, there is another dry chamber, which was discovered during a previous expedition. During the 2023 expedition, team members thoroughly examined it, but apart from discovering another entrance hole, they did not find any corridors.

Unfortunately, the 2023 exploration of Köldhålet did not yield significant discoveries other than a few smaller corridors totaling 57 meters in length.