13 jaw-dropping caves you can safely explore — mashable.com

Man left the cave centuries ago, but we're still diving back in for different reasons. The beautiful natural structures peak our interest, feed our hunger for curiosity and educate us on this mysterious planet. Modern equipment has brought caving, also known as spelunking, to new and dangerous depths. But most couch surfers and tourists don't really want to risk their lives for a sneak peek inside the Earth.

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