Great Barrier Reef (9pm, Animal Planet) - A two-hour special exploring the Earth's largest living structure, the Great Barrier Reef beneath the Coral Sea. The series of interconnected habitats spans 1,200 miles and is so large it can be seen from space.
Drop Dead Diva (9pm, Lifetime) - In the season finale, Grayson reveals his true feelings for Jane on her wedding day, and Parker discovers Kim's secret. Also, a woman refuses life-saving surgery to remove a tumor because the cancer has suddenly made her brilliant, and a songrwriter is sued over claims that her lyrics lead fans to attempt murder.
Hell on Wheels (9pm, AMC) - Cullen's past catches up with thim and threatens the fate of the railroad.
Leverage (9pm, TNT) - Parker breaks her leg and is left behind on a job, only to then happen upon a robbery scheme.
Army Wives (10pm, Lifetime) - In the season finale, news spreads that Fort Marshall will merge with an Air Force base, and Kevin experiences a medical breakthrough. Also, the troops return to Afghanistan. Hopefully this is a season finale and not a series finale...
Web Therapy (10:30pm, Showtime) - In the Season 2 finale, Fiona cures the overly obsessive Newell, but her handling of Robin has disastrous ramifications for Kip's campaign.