People like to compare Slovenia with the Emmentaler cheese. The karst caves are spread over the entire region. Among them Postojna cave is the most visited cave in Europe, featuring also the most exciting subterranean train ride on Earth. Skocjan caves are a bit less visited, though Lonely Planet sees them as one of the top ten attractions in this part of Europe. At 60m wide and 140m deep, they are one of the biggest underground canyons in the world.