The biggest mystery 20,000 leagues beneath the sea is uncovered when SpongeBob and the gang find the lost city of Atlantis! To celebrate the monumental underwater discovery, Nickelodeon will blow it out of the water all day long with a SpongeBob convergent online and on-air event on Monday, November 12, from 9:00 a.m. to 9:00 p.m.

Kicking-off the 12-hour marathon of kids’ favorite episodes from “Z to A” will be the theatrical film "The SpongeBob Square Pants Movie" (9-10:30 a.m.). The event will culminate with the premiere of SpongeBob’s “Atlantis SquarePantis” TV movie guest starring David Bowie and the “Behind the Pantis – How We Made Atlantis SquarePantis” special (8-9 p.m.), all times ET/PT. Also integrated throughout the day, Patchy the Pirate (Tom Kenny) will host his own talk-show from the bottom of the aquarium at the Atlantis Hotel in the Bahamas with special guest star Devon Werkheiser of Ned’s Declassified School Survival Guide and navigate viewers through the episodes that kids voted for online on TurboNick.

In the TV movie, “Atlantis SquarePantis,” (8-8:45 p.m.), SpongeBob finds the missing half of an ancient medallion believed to be a relic from the lost city of Atlantis and brings it to the Bikini Bottom Museum where the other half is on display. The two sides are reunited, and suddenly a magical van appears that beckons to take SpongeBob, Patrick, Sandy, Squidward and Mr. Krabs to the legendary city of Atlantis. Each passenger, along with Plankton who has secretly stowed away in the van’s glove compartment, is eager to experience the many riches the city is rumored to contain. When the van finally arrives, they are greeted by Atlantis’ king himself, Lord Royal Highness (voiced by David Bowie), who spares no time in taking the visitors on a tour. Atlantis proves to be even more wonderful than anyone could have imagined, particularly for SpongeBob and Patrick who encounter the Oldest Living Bubble. But when a flash from Patrick’s camera causes a mishap, SpongeBob, Patrick, Mr. Krabs, Sandy and Squidward must run from the Atlantean Guards or find a way to make amends.

Immediately following the TV movie (8:45-9 p.m.), Nickelodeon will premiere it’s first-ever Nicktoon behind-the-scenes special, “Behind the Pantis – How We Made Atlantis SquarePantis.” The special delves into how the TV movie was created, from the initial story pitch, writing, storyboarding, drawing and animation to the voice recording sessions.