Deep beneath the domes and spires of Kiev’s Old Town, and unbeknown to the crowds who flock to the monasteries, monuments and cathedrals above, there exists another world.

Of course, Ukraine boasts more than its fair share of appealing destinations for urban explorers – from the Chernobyl Exclusion Zone to the Odessa Catacombs – and yet surprisingly little has been written about the vast network of drains, tunnels and mines, which spread for many miles beneath the capital city of Kiev.

I was lucky enough to receive the guided tour of Kiev’s secret underworld, courtesy of General Kosmosa. It’s a good thing, too – the winding passages and restrictive tunnels that form this subterranean network seemed to branch off in all directions, some leading deeper into disused mines beneath the city, others culminating in abrupt dead-ends.

We entered the tunnels through a simple wooden hatch set in a concrete base, located in a stretch of rough ground near the city’s financial district. As I climbed carefully down the ladder and into the darkness, patches of rust and limescale came off the rungs in great, wet flakes – staining my palms a livid shade of orange.

The first trapezoid tunnel we entered into seemed to stretch on forever, a corrugated tube of concrete that faded to black in both directions. With the General leading the way, our party of three made our way upstream through the darkness, cold water rushing past our feet at ankle level. The uniform tunnels were roughly five foot in height, forcing us to hunch over as we trudged onwards.

From this main waterway a number of passages forked off at tangents, each one disappearing into dark spaces filled with the sound of running water. At one point I managed to loose sight of the others, while pausing briefly to take a photograph – running to catch up I took the wrong turning where the path divided neatly in two. It only took me a few minutes to realise I had gone the wrong way and find the rest of the group, but the experience brought home the very real danger of getting lost in this labyrinthine underworld.

After ten, maybe even twenty minutes of the same endless, corrugated tunnels (my awareness of time decreasing inversely to my developing night vision), we reached a vertical shaft. This narrow opening at the end of the tunnel had the appearance of a subterranean waterfall; a metal ladder set into the back wall, obscured behind a cascading torrent of cold water.

Torch and camera stowed safely inside a waterproof bag, I followed my guide up the ladder – the water quickly soaking me to the skin, and making for a slow and treacherous climb.

On this next level the ribbed concrete tunnels gave way to rough-hewn rock, and more than once I cracked my head on low-hanging stalactites. Another five minutes upstream however the tunnel finally opened up above us, and we entered into a vast, vaulted chamber. Fractured light spilled in from the slatted roof, illuminating the deep, round shaft – lined with concrete roundels and hung with rusted gantries – in which we now stood.

Far above our heads, beyond the iron grating, lay the heart of Kiev’s financial district. Many of these tunnels were installed as a back-up water supply by Stalin, during the Soviet era. However, these newer sections were merely extensions to a much older network of tunnels, which riddle the ground beneath the city – as we were to find out by delving deeper into the warren of pipes and passages.

Initially we tried following the other main passage feeding into this central chamber, but we didn’t get far before finding our path blocked by fallen rubble.

Seemingly unperturbed, our guide led us back to the last chamber; choosing instead a smaller, rocky shaft that led off at a tangent. I found myself wondering (and not for the last time) how he had managed to commit to memory such a complex network of tunnels.

The next excitement came as our path opened up onto a large vertical shaft; here the slow stream we had been following trickled out along an extended lip, high above the floor below, before cascading down a drainage funnel. We were granted no such conduit however, and so upon reaching the slippery overhang we had to climb across onto a rusted metal gantry fastened to the wall nearby. From here it was possible to make one’s way down a series of iron ladders, suspended at varying angles in a haphazard zigzag pattern… a precarious climb indeed, down four flights of slippery, rust-encrusted rungs.

From here we trekked through a long concrete tube, resembling a scaled-down train tunnel. After perhaps ten minutes, the end not even nearly in sight, General Kosmosa stopped us by a side turning. Here the tunnels were much smaller, older, and cut in two by the newer installation.

The General told us that these were the remains of a system of mine shafts, dating back to the mid-nineteenth century; and as we crawled along the narrow shaft, I found myself imagining what it must have been like to work these mines, so far removed from the light of day. The air tasted thin, and fungus grew from the damp walls.

Occasionally we found traces of life – alcoves set into the walls held spaces for bowls and flasks, places where miners would stop to rest or refresh themselves.

At times the progress was almost unbearable. The passages were so small that movement was severely limited; the ceiling often pressing low enough that we were forced to pull ourselves forward on our elbows.

As the cold water continued to splash around my forearms, sometimes reaching as high as my chin, I prayed we wouldn’t encounter a flash flood – it would have been near impossible to reverse out of such a confined space.

Not only did the tunnel seem to be without an end, but it was also noticeably decreasing in size. I had almost reached the point of questioning our guide’s sanity, when finally we came across a junction, and dragged ourselves out of the rocky shaft and into one of the newer concrete tunnels.

From here it was an easy walk to our exit… we emerged much as we had entered the drains, through a nondescript hatch set in a patch of rough ground. Fresh air had never tasted so sweet. We dried ourselves as best we could, changed our clothes, and I threw my ruined shoes in the nearest bin. After that we bought a few bottles of strong Ukrainian beer and sat on a wall in the park, watching the sun go down over the city.

All in all a fantastic day out, and a great first foray into the underside of one of Europe’s most beautiful cities. Thanks once again to General Kosmosa for making this expedition possible… and if you’re interested in keeping up to date with his adventures, then you can pay a visit to his own urban exploration blog here.