Offshore flooded caves, so-called ocean blue holes, are extensions of the sea, subject to the same heavy tides and host to many of the same species found in the surrounding waters. Inland blue ...

Explorers descended into a 500-foot-deep cave—only to find something even more mysterious below: a perfectly blue, seemingly bottomless hole. Learn what makes this rare geological formation so ...

Explore what makes the Blue Hole one of the world's most dangerous diving locations. President Trump answered a cold call ...