韩松洞，风牙者榜国家公园，越南 Hang Sơn Đoòng cave, Phong Nha-Kẻ Bàng National Park, Vietnam (© Geng Xu/Getty Images)

韩松洞，风牙者榜国家公园，越南 Hang Sơn Đoòng cave, Phong Nha-Kẻ Bàng National Park, Vietnam (© Geng Xu/Getty Images)

“洞”之新世界 A 'hole' new world

韩松洞，风牙者榜国家公园，越南

1991年，一名越南伐木工人在越南的风牙者榜国家公园偶然发现了一个大东西。在丛林探险时，他发现了一个洞穴的入口，里面有着咆哮的地下河，后来被命名为韩松洞，即“山水洞”。2009年，英国洞穴研究协会率领一支探险队对该遗址进行了勘探。就在那时，他们发现了一件不可思议的事：这是世界上最大的洞穴！你要问有多大？韩松洞的主要通道长3.1英里，宽490英尺，高660英尺。它的高度足以容纳一座40层的摩天大楼！里面有一个200英尺高的方解石屏障，被称为“越南长城”，石笋高达260英尺。它甚至有自己的天气系统；由于洞穴空气和外部空气之间的温差，洞内形成了云层。此外，一条地下河流将韩松洞与附近的洞穴连接起来，暗示着还有尚未被发现的深度。鉴于其脆弱的生态系统，为保护韩松洞的原始状态制定了严格的规定。每年参观洞穴的游客数量限制在1000人以内。

Hang Sơn Đoòng Cave, Vietnam

In 1991, logger Hồ Khanh stumbled upon something big in what is now Vietnam's Phong Nha-Kẻ Bàng National Park. During a jungle expedition, he found the entrance to a cave with a roaring underground river. It was later named Hang Sơn Đoòng (cave of the mountain river) and in 2009, the British Cave Research Association led an expedition to explore it. They realized something incredible: It was the world's largest cave. Hang Sơn Đoòng's main passage is 3.1 miles long, 490 feet wide, and 660 feet high. That's tall enough to fit a 40-story skyscraper.

Inside the cave, there is a 200-foot calcite barrier called the 'Great Wall of Vietnam' and stalagmites stretching as tall as 260 feet. It even has its own weather system; clouds form inside due to temperature differences between the cave air and the outside air. Moreover, an underground river links Hang Sơn Đoòng to the nearby Hang Thung cave, suggesting undiscovered depths. Given its fragile ecosystem, strict regulations are in place to preserve Hang Sơn Đoòng's pristine condition. Tours of the cave are limited to 1,000 visitors per year.