"Some of Earth's strangest-and creepiest-wonders lie deep below the surface. There's Lake Natron, a Tanzanian lake so briny that its waters can mummify any creature that touches its surface; Lake Maracaibo, a Venezuelan tidal bay where a constantly brewing storm sends an average of 28 lightning bolts per second into the water; and at the bottom of Lake Superior, the crew of the USS Kamloops-which mysteriously disappeared in 1921-remains somehow almost...