Situated deep in the often frozen wasteland of Siberia, Lake Baikal has enchanted locals and visitors for generations. Come there in the summertime and you'll see nothing out of the ordinary: families picnicking, people fishing, and hikers going for long walks to see the wildlife. But there's something far more special to the lake than just its landscape - and it could be one of the world's greatest secrets.
It's hard to imagine anything as flashy as an alien base just hiding out in a little old lake. But while Lake Baikal might be old - positively ancient, in fact - it's certainly not little. From end to end it's just under 500 miles and it covers an area of 12,000 square miles. Not only that, but it's the deepest freshwater lake in the world, reaching a massive 5,400ft down. If that's not enough to squeeze in a hideout, we don't know what is.