He lives in a pineapple under the sea. He’s Spongebob Squarepants.

The popular cartoon character has been a star on television for the past five years. Now, creator Stephen Hillenburg says it was time to bring Spongebob to the big screen in “Spongebob Squarepants: The Movie.” The movie opens this weekend.

“We reached a point in the show when we were ready to expand,” he says. “[We wanted] to see Spongebob connect with our world.”

On the television show, Spongebob is not only a big hit among children, but also among teenagers and young adults. Hillenburg, also a director and writer for the film, says he credits Spongebob’s broad success to retaining a youthful and optimistic spirit throughout the show.

“At one point, everyone was, or is now, a kid,” he says. “There’s a real connection to the characters.”

That running theme was an important part of the show, Hillenburg says, so he and his team of writers, animators and voice actors were sure to retain it when they transitioned Spongebob to the movie screen.

“The movie reinforces a childlike perspective, and to keep it,” Hillenburg says. “There’s a great resource in kids.”

But the transition wasn’t easy. Hillenburg says moving from a show — where skits are 11 minutes long — to a 75-minute movie proved to be quite a feat.

“It was a whole different animal,” he says. “It’s hard to write a movie and keep people interested for 75 minutes.”

One of the biggest challenges for this movie was putting Spongebob into a new — human — world. Since Spongebob would be coming out of the ocean, Hillenburg says he decided to implement the best actor for the part — David Hasselhoff.

“We wrote him into the story without asking first,” Hillenburg says. “He just really nailed it. His performance is so over-the-top and funny.”

But Hasselhoff isn’t the only star featured in the film. In addition to the regular cast of voice actors from the show, characters are also voiced by Scarlett Johannsen, Alec Baldwin and James Earl Jones.

The other stars of the film are the numerous bands featured on the soundtrack. Featuring a lineup of rock bands such as Ween, The Flaming Lips and The Shins, the soundtrack has been praised for attracting such talent.

James Mercer, lead singer of The Shins, says he was a big fan of the show, remembering fond memories of watching the show with folks he had lived with in Portland.

Mercer says the choice to contribute a song to the soundtrack was easy. Instead of writing a completely new song, he says, he decided to work on a previous song which he was struggling to finish for one of his albums.

“I really couldn’t make it work,” Mercer says. “It sounded too bubblegum and cartoony. That worked out good [for the soundtrack].”

The sound of the song may surprise some fans, Mercer says, but it’s perfect for the material it complements.

“It’s different from what I’d put on a normal album,” he says. “I’m still proud of it.”

This is the second time this year that The Shins were featured on a movie soundtrack. The other film, “Garden State,” not only featured two of their songs on the soundtrack, but also had one character, played by Natalie Portman, mention the band that can change one’s life.

“That’s more advertising than any band can hope for,” Mercer says.

Mercer says working on a song for the Spongebob soundtrack was a unique experience — creating a song that did not immediately try to grab the audience’s attention. He says the process is almost like the opposite of writing other songs.

“You don’t want your song to stand out or detract from the movie,” Mercer says. “It’s hard to not write a song.”