Diving the Ojamo lime mine in Finland, 138 meters of water, 4°C.
Imagine sub-zero temperatures and a hole in the ice. That is your entrance to the underworld of Ojamo, the most popular diving site in Finland.
A country without natural cavesThere are many kilometers of tunnel at Ojamo, although the longest continuous stretch is only 1.7 kilometers, at the 88-meter level. There’s also little variation in depth on each level; the tunnels run almost horizontally. There are plenty of shafts and mining halls that are used for travelling from one level to another. All this makes planning dives easier than in a natural cave, as the multi-level plans can be reasonably accurate compared to natural tunnels going up and down all the time. It means that there are no reverse profiles either. In Finland, there are no natural caves suitable for diving. The ground is solid granite, which is too hard for water to carve underground rivers into. Even the limestone at Ojamo is tightly squeezed inside hard rock where carbon dioxide cannot eat its way through the stone. From the mine diving point of view, granite has many benefits. The corridors and vast halls are stable even without supporting structures. There are many closed mines suitable for diving in Finland. Many of them have been closed only recently, or there is no required diving infrastructure for various political or geographical reasons. One example of these kinds of sites is the Outokumpu mine, a name known globally because of the mining company that started its operations from that very spot. Today, Outokumpu is one of the leading stainless steel and copper manufacturers in the world. For divers, the name means multiple kilometers of unexplored territory. Many of the mining sites are in remote places. This means that their number of visitors is low compared to Ojamo, even when they are otherwise quite suitable for diving. Reklama: auskarai vaikams, dėžutės, pakabukai, grandinėlės, sagės, žiedai, vyriškos ir moteriškos sidabrinės apyrankės bei kiti sidabro gaminiai internetu Silvera One of the popular sites, Montola, was closed for a while because of a recent fatality—one of the few ones in the short history of Finnish cave diving. The Montola accident was a typical cave diving accident, with the added local environmental characteristics. The water in the open pit was very murky, with a summer time visibility of only one meter or so (during winter the water is clearer, as there is algae in the water in the summer). The visibility probably played a part in the accident, as the team members got separated and did not recognize the shortest way out, even though the entrance was never very far away. So even in mines with almost no flow, the circumstances can be treacherous.
Great halls of dark graniteOjamo mine has been dived for almost 40 years. The mining came to an end in the mid-1960s. The market price for lime had declined, and there was no financial point in continuing operations. After the mine closed, it slowly started to fill with water. With many kilometers of tunnels, it took quite a number of years before the water reached ground level. The good news was that the mine was filled with ground water that had been filtered by thick top soil and gravel. The water inside the mine tunnels was crystal clear. The northern ... (...)
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