Hey ho! Silence. We know what it means. Cavers returning. The kettle lets out a hisssss and gurgles. A tackle bag falls heavily on the floor and we all look up. “Hey ho!” And conversations resume, “Yes this word fits”, “What about fifteen down ?”, “Does it go?”, “Tea is up!”, “Where’s the cow ?”

I am sat in the bivi, a large depression with an overhanging rock bridge on the Migovec Plateau in the Triglav National Park, Western Slovenia. From the Sunset Spot, one can gaze all the way to Italy and during a clear sunset one can even spot the Dolomites rising in the distance, shadows crowned with russet light. West of Migovec is the Krn massif, former Soča front during WWI, sometimes wreathed in storm clouds while stars twinkle upon Migovec.

Those are the first things I learnt as an expedition Fresher. Then come the more prosaic rules: when and how to use the toilet facilities (a dignified pit), not falling into M10 (a 30 metre open pitch) when leaving the bivi at night, where to pitch the tent, how to successfully manufacture a ‘dwarf pine sofa’ etc…

Living for five weeks at 1850 metres of elevation, three hours from civilisation is almost as remote as you can get in terms of summer expedition. Water? Collected with tarpaulins into barrels. Electricity? Collected via solar panels. That’s the problem with a ‘hollow’ mountain: there are no overground streams for water collection or electricity production. Food? Hunted for in British supermarkets and cooked on petrol stoves. There is always the latest teaspoon spinning device available and a myriad of other ingenious contraptions to make mountain life easier. To quote the expedition veterans “they must invent not just explore”.

I am sat in the bivi, discussing possible leads with the old lags and the returning cavers. I book four nights in the underground camp and start preparing my kit. Tomorrow, another caver and I are going to explore at –700m with a chisel, crowbar, and hammer. We have a 600kg rock to shift in order to squeeze past. I hear tales of the chamber beyond, and the roar of a waterfall afterwards. As excitement builds up, so does apprehension. I’ve been down at underground camp, I’ve been at the southern most point of the cave, a good three hours from camp and from there five hours to the surface. But I’ve never slept at camp X-Ray more than two nights in a row, and I’ve never done more than one pushing trip. There’s no knowing what you sign up for when going pushing which is either thrilling or sobering.

The next day we set off in pair and walk to the cave entrance, a few minutes off the bivi. We enter the cave. 98 hours later, we make it out, exhausted and elated. It is four in the afternoon and we enjoy the smell of dwarf pine mixed with earthy fragrances we were starting to miss. The temperature is a delight after the ubiquitous 1°C of the cave. Twenty minutes later we arrive at the bivi.

“Hey ho!”

Silence.

“Does it go?”

“Do you want some tea?”

“Yes”

“Cow?”

“No”…

“Yes the cave goes, it always goes, the mountain is hollow after all.”

After the rock was shifted – it took us three hours – we found a small chamber, at the end of which a pitch head awaited us. So we rigged it the day after and descended into an active streamway. Not the roaring torrent we were expecting but some water nonetheless. From then we crawled into an oblique rift and found another pitch head. Whilst clearing it of unstable boulders, one rock shifted into the gap and obstructed the way on.

The day after, with a chisel and crowbar we attacked it until it yielded another chamber, more rift and a third pitch. This we descended on the last day, and walked down more tight rift, free climbing over pristine pools of water until we were faced with a last circular shaft, seven metres deep. We surveyed our finds, slept at camp and got out.

“Shall we enter the survey data now?”, “Of course”. And little by little the 150 metres or so of passage are added to the grand survey. What a joy to see four days worth of work take shape before one’s eyes! Where does it head to? Is it blank mountain? As ever we raise more questions than we actually answer.

There lies the thrill of exploration: more people have been to the Moon than in the passage we found. Tomorrow though is the expedition D-Day. This is the final caving day when we will put the cave to sleep for another year by packing up camp X- Ray and finally head down to Tolmin the nearby town in the valley before the long journey home. Migovec, I’ll be back.