At Crater Lake National Park, the deepest lake in the U.S. is slated to close to swimmers and boaters for two years.

Day trippers can enjoy diving from a nearby 11-meter cliff face into the clear blue depths of the waterway, which sits in the blown-out caldera of a once mighty volcano known as Mount Mazama.

More than 7,700 years ago, an ancient volcano named Mount Mazama erupted and caused the peak to collapse in on itself. Over the centuries, snowmelt and rainwater filled the yawing crater to create ...