The Orda (or Ordinskaya) Cave is located in Russia's Perm Region, at the border of Europe and Asia. The cave system measures 14,435 feet long, and almost the entire length is underwater. In terms of the size of its underwater galleries, it's one of the biggest caves of its kind in the world. And while you wouldn't want to get lost down there, it makes for some spectacularly beautiful photographs.
Viktor Lyagushkin took these pictures while he was diving with his wife. They're part of a book project called 'Orda Cave Awareness'. His wife, Bogdana Vashchenko, told Environmental Graffiti that swimming the caves "was an incomparable delight, floating in zero gravity in giant rooms filled with absolutely clear water".
Take a look at some of Viktor's photographs below:
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