Nature
Invasion of the Giant Pythons
Wednesday, June 19, 8:00 pm ET

Florida’s Everglades National Park is one of the last great wildlife refuges in the United States, home to numerous unique and endangered mammals, trees, plants, birds and turtles, as well as half a million alligators. However, the Everglades is also the dumping ground for many animal invaders — more than 15 species of parrot, 75 kinds of fish and 30 different reptiles from places as far away as Africa, Asia and the Caribbean. All of the intruders found their way into the park either by accidental escape from pet owners or intentional release by people no longer wishing to care for an exotic species. Add to the mix tens of thousands of giant pythons, snakes that can grow to 20 feet and weigh nearly 300 pounds, some released into the wild by irresponsible pet owners, some escapees from almost 200 wildlife facilities destroyed by Hurricane Andrew in 1992. The predatory pythons slithered into this protected wilderness and thrived, and the refuge has consequently become less a haven than a killing ground every day since then.

NOVA
Extreme Cave Diving
Wednesday, June 19, 9:00 pm ET

This program follows the charismatic Dr. Kenny Broad as he dives into blue holes — underwater caves that formed during the last ice age when sea level was nearly 400 feet below what it is today. The holes are Earth’s least explored and perhaps most dangerous frontiers. With an interdisciplinary team of climatologists, paleontologists and anthropologists, Broad investigates the hidden history of Earth’s climate as revealed by finds in this spectacularly beautiful “alternate universe.”

MASTERPIECE: MYSTERY!
Inspector Lewis, Series VI: The Ramblin' Boy
Sunday, June 23, 9:00 pm ET

With DS Hathaway on holiday, Inspector Lewis is assigned a new partner to investigate the discovery of an elderly man’s body in a field. Finding that the man had already been embalmed, the inquiry leads to a funeral home and those connected to it, including one of Lewis’ former colleagues. Peter Davison (“Doctor Who”) guest stars.