Muppets Underwater is a nonexistent Muppet film often cited by Jason Segel as the type of film he was trying to get the Muppet franchise away from when he and Nick Stoller were developing the 2011 film The Muppets.
Throughout 2008, while doing publicity for his films Forgetting Sarah Marshall and I Love You, Man, Segel often mentioned the fictional film—occasionally along with such other nonexistent Muppet projects as Muppets in the Sahara, Muppets in the Old West, and Muppets on the Moon—when describing the type of bad "concept films" he felt the Muppets had been producing. Segel continually stated he didn't want to make a novelty film with a central gimmick, like "Muppets Underwater," but rather he just wanted to make a classic film where the Muppets get together to put on a show.
Ironically, Segel wrote a segment for The Muppets in which Kermit's car has the ability to travel by map, including a shot in which the vehicle is shown to have driven under the Atlantic Ocean whilst full of Muppets: Muppets underwater.
- Segel told MTV: “I've just grown a little disappointed with 'Muppets in the Old West,' 'Muppets Underwater,' and all these weird concept movies. I just want to go take it back to the early 80's, when it was about the Muppets trying to put on a show. That's what I’m trying to bring back."
- Segel told IGN: "I'm bringing it back to the early 80s Muppet movies. No more of this 'Muppets in Space' or 'Muppets Underwater.' It's the Muppets putting on a show. You know, like old times." 
- Segel told the New York Times: "I want to revive [the Muppets] to their previous glory, before they became a novelty act. When it wasn't, like, 'Muppets Underwater.' 'Muppets in the Sahara.' 'Muppets on the Moon!'"
- Segel told Rolling Stone: "We are trying to bring the franchise back to the perfect tone they had established in the early '80s. No more 'Muppets Underwater.' This movie is about the Muppets putting on a show to help each other out. Simple and heartfelt."
- Segel told MovieWeb: "We are trying to bring it back to the early '80s movies where it's not 'Muppets in the Sahara' or 'Muppets Underwater.' It's the Muppets getting back together to put on a show, to save the studio."
- Segel told ComingSoon.net: "All I can say is that we are trying to bring it back to the early '80s movies where it's not 'Muppets in the Sahara' or 'Muppets Underwater.' It's the Muppets getting back together to put on a show, to save the studio."
- Segel told Canwest Press: "They've started churning out these straight-to-DVD movies. I don't know. The original Muppet movies could have been done with humans. They were about putting on a show, and laughter, and fun, and all that stuff. So we're trying to bring back that same spirit to the new one, to our movie, where it's about the Muppets putting on a show. There's no novelty to it. It's not 'Muppets in Space' or 'Muppets in the Sahara' or 'Muppets Underwater.' It's a proper film."
- Segel told Delta Sky Magazine: "Nick [Stoller] and I just came up with an idea that made so much sense. As soon as you come up with the idea that the Muppets are disbanded throughout the world, it becomes a reunion movie. Which is a much bigger event than just another Muppet movie, where it’s like 'Muppets Underwater' or something."
- ↑ MTV News: Jason Segal Ready to Get Things Started with the Muppets March 17, 2008.
- ↑ IGN: The Muppets Go Old School March 18, 2008.
- ↑ THe New York Times: A Young Actor with Nothing to Hide April 13, 2008.
- ↑ Rolling Stone: Rolling Stone News June 2008.
- ↑ MovieWeb: Jason Segel Spills More About His Muppet Movie June 8, 2008
- ↑ ComingSoon.net: Love You, Man Set Visit: Jason Segel June 8, 2008.
- ↑ Canada.com: The Muppets Return August 14, 2008.
- ↑ Sky Magazine: A Frog We Can Believe In December 2011.