Phong Nha Cave isn't the biggest cave, or even the second-biggest, in the Phong Nha National Park. But it's the one which bears the park's name. So we felt safe assuming that it would be spectacular. And we weren't disappointed; this is an underground wonderland of stunning beauty.
We spent four nights in the Phong Nha National Park, which is home to more than 300 caves including, incredibly, two of the world's three largest. On our first full day in the park, we embarked on a long hike through the forest to visit two of the regular-sized caves, one of which we'd be swimming through.