Some of Thailand’s biggest and most beautiful caves are all the more intriguing because they have been discovered only in the past decade. Yet all the superlatives must be couched in tentative terms (such as the “tallest known column”) because there are certainly more caves to be unearthed.

“Discovered” may not be the most accurate term. Frequently local villagers have known for countless generations that a nearby cave existed, but they had never ventured very far within because they feared ghostly occupants or lacked proper lights and equipment. The recent teams of foreign cavers therefore have often found themselves to be the first people to enter an underground chamber with a 15-metre high ceiling or to gaze upon a thousand-year-old flowstone resembling a frozen waterfall.

Geologists pinpoint likely cave sites by examining maps and the ground composition. Kanchanaburi and the northwest are prime cave country because most of the rock base is limestone. Limestone is easily dissolved by the mildest acidic solutions, such as that created by rainwater mixed with decaying plant matter. Before humans existed, the corrosive rainwater cut through limestone cracks and slowly formed underground channels. Over centuries, the channels merged to create tunnels and caves.

Caves that were created over millions of years appear to be very durable. Yet human visitors are only one threat. The porous nature of the stone means that run-off from pesticides or fertilizers can readily kill plants, fish, insects, snails, spiders or snakes in a downstream cave. The culprits aren’t only little people. Dam builders are guilty too when caves are damaged due to rivers drying up.

Why are Thai caves valuable? Their limestone formations, in a dazzling array of shapes and colours and sizes, most immediately come to mind. They also shelter plant and animal species that are rare if not unique. Less well known is that caves promise to reveal something of the history of the earliest people to live in what is today Thailand. Australian John Spies, a veteran caver, has seen in 70 caves the remnants of teak coffins dating from 1,600 to 1,700 years ago. He himself lives on the Lang River in Mae Hong Son Province within walking distance of Lod Cave. That cave has ten ancient coffins tucked in high rock shelf. The coffins were probably left by ancestors of the Lawa tribe, which lived in the north long before the arrival of Tai people. Artifacts and the remains of plants and seeds found in other caves suggest that farmers dwelled in the north more than 10,000 years ago, he said.

Caves aren’t only museum pieces. Well-maintained caves can also earn their keep. Colleen Jones, a Canadian forester working at Sri Nakharin National Park, said that wherever a cave needs optimum protection, there’s usually an interesting one in the vicinity which can withstand tourism. Spies noted that all 70 households in the Shan village neighboring Lod Cave have benefited from the small but steady flow of tourists in the past ten years. Most households count a member acting as a tourist guide to the 1.6 kilometre through-cave. As a result, the villagers are now less dependent on slash-and-burn farming … ∩

This sidebar accompanied a news story about a cave with a 20-story-tall column that was to get national park status. I wrote it for The Nation newspaper. Thailand has fantastic caves, probably hundreds of them. There are many aspects that would make for good, lavishly illustrated feature stories.