The Pennsylvania Department of Environmental Protection says it has learned where the lead in Blue Hole Creek is coming from.

At the bottom of a 500-foot deep cave lies a stunning discovery - a deep blue hole hidden from the world above. In this video ...

Nestled along Route 66 in Santa Rosa, New Mexico, the Blue Hole is a captivating artesian spring renowned for its ...

The blue water spring is about 13 feet in diameter and 1 foot below the rim, USGS said. The water in the pool was measured at ...

The Dragon Hole is about 990 feet deep, surpassing the third-deepest blue hole, Dean’s Blue Hole, by over 300 feet. The Taam Ja’ Blue Hole is more than twice as deep as Dean’s Blue Hole.

It's a limestone cave, to be exact. The Great Blue Hole contains stalactites and stalagmites below the surface, some 40 feet in length. And as with any good cave, more mysteries lie within.