He’d travelled more than three miles through the earth by then, over stalagmites and boulder fields, cave-ins and vaulting galleries. He’d spidered down waterfalls, inched along crumbling ledges, and bellied through tunnels so tight that his back touched the roof with every breath. Now he stood at the shore of a small, dark pool under a dome of sulfurous flowstone. He felt the weight of the mountain above him—a mile of solid rock—and wondered if he’d ever find his way back again. (via In Deep - The New Yorker)
Click through! The article is well-worth the read for far more reasons than just marveling at the vast complexity of deep “architecture.” But it also details nice subterranean design:
"When prospecting for deep systems, cavers start in mountains with thick layers of limestone deposited by ancient seas. Then they look for evidence of underground streams and for sinkholes—sometimes many miles square—where rain and runoff get funnelled into the rock. As the water seeps in, carbon dioxide that it has picked up from the soil and the atmosphere dissolves the calcium carbonate in the stone, bubbling through it like water through a sponge. In Georgia’s Krubera Cave, in the Western Caucasus, great chimneylike shafts plunge as much as five hundred feet at a time, with crawl spaces and flooded tunnels between them."
"Deep caves rarely call attention to themselves. Like speakeasies and opium dens, they tend to hide behind shabby entrances. A muddy rift will widen into a shaft, a crawl space into a vaulting nave. […] The bigger the cave, the more air goes through it, and Krubera was like a wind tunnel in places. ‘If it blows, it goes,’ cavers say."
Interesting to note that deep-cave exploration must be done in a similar manner to mountaineering, with base camps. That can set up a lovely bit of storytelling.
Finally, some perspective on the end of an adventure. Every underground adventure should feel like this afterward:
"On their twenty-first day underground, when they finally emerged from the cave’s rocky clutch, they blinked up at the sun like newborns. Their skin was ashen, their eyes owl-wide and dilated. [I]t had also been the longest and hardest trip he’d ever taken, and it made the return to the surface all the sweeter. The green of the forest, so luminous and deep, seemed nearly psychedelic after weeks of dun-colored earth and the pale wash of his headlamp. The smell of leaves and rain and the workings of sunlight were almost overwhelming.
”’[…]When I’m back on the surface, just by contrast, I enjoy every piece of my life. Everything is fantastic.’ He laughed. ‘Some people say that all this caving is just for a better taste of tea.’”