NEW YORK — Here are some things I learned in my 2½ hours of attendance at the new Broadway musical version of “SpongeBob SquarePants”:

  1. A squirrel can be both ambiguous and amphibious.
  2. Ethan Slater, who plays SpongeBob, is a kind of genius.
  3. A starfish often makes a good point.
  4. Tina Landau and David Zinn, who directed and designed “SpongeBob,” are other types of geniuses.
  5. For dazzling tap routines, a squid has a natural advantage.
  6. To really appreciate the multitudinous shenanigans of “SpongeBob SquarePants” the musical, you have to have been there.

And by “been there,” I mean spent some quality time in Bikini Bottom, the village teeming with animated marine life where SpongeBob lives. Listening to the hooting by millennial members of the audience in the Palace Theatre, where the super-bubbly musical had its official opening Monday night, I realized I had failed to adequately steep myself in the aquatic folkways of Bikini Bottom. In other words, lacking a familiarity with the voluminous Nickelodeon library and a SquarePants archive going back to the first episode in 1999, I was ill-equipped to be an authoritative consumer of the many inside jokes that had other theatergoers in stitches.

I can tell you this: Much impressive design and engineering work has gone into this $20 million production, which has been guided with an eye for childlike delight by Landau, in concert with Zinn, who designed the exuberant neon-colored sets and costumes, and Christopher Gattelli, who staged the dances — the tapping by the four-legged Squidward Q. Tentacles (Gavin Lee) and a school of sardines being a particular joy. And the athletic Slater, meantime, proves to be a totally winning SpongeBob, accomplishing the unusual trick of seeming to exist simultaneously in two dimensions and three. Blessedly, a decision was made not to outfit Slater like the cartoon character; the actor’s uncanny physicalizing integrates both a distinct personality and a cartoon aesthetic.

And still: I can’t see recommending this show to anyone except true “SpongeBob” buffs. Some of the songs, by an array of artists including Steven Tyler, John Legend, the Plain White T’s and Panic! At the Disco, are jaunty and expertly integrated into the story: Yolanda Adams’s “Super Sea Star Savior,” for Patrick Star (a terrific Danny Skinner) and the Sardines, and Legend’s “(I Guess I) Miss You,” for Patrick and SpongeBob, are especially charming.

It’s the story that consigns “SpongeBob SquarePants” to the novelties department. Book writer Kyle Jarrow has fashioned a lumbering plot that’s too dull for a show of this scale and ambition. The drawn-out tale is about a volcano threatening to destroy Bikini Bottom, whose denizens are counting on SpongeBob and Sandy Cheeks the squirrel (Lilli Cooper) to save the day.  Where, you ask, does a squirrel fit in? I’ve since been informed by my daughter, who was 7 when the series premiered, that Texas-born Sandy lives in a biosphere. As I said, you sort of have to have been there.

In the family-friendly vein, another production of endearing pedigree had its official opening this week on Broadway, this one a first-rate revival of Lynn Ahrens and Stephen Flaherty’s 1990 tropical folk tale “Once on This Island.” Director Michael Arden (Deaf West’s “Spring Awakening”) and set designer Dane Laffrey do a grand job of transforming the in-the-round stage of Circle in the Square Theatre into a Caribbean beach to recount the ill-starred love of a disadvantaged orphaned girl (Hailey Kilgore) for a boy (Isaac Powell) from a rich island family.

The 90-minute musical is favored with some rich and rollicking Ahrens and Flaherty melodies; Alex Newell’s “Mama Will Provide” will get your blood pumping, and the heartfelt performances will put you in a generous frame of mind — at a time of year when spreading good cheer is the general idea.

SpongeBob SquarePants, book by Kyle Jarrow, original songs by artists including Steven Tyler and Joe Perry of Aerosmith, Cyndi Lauper and Rob Hyman, John Legend and Panic! At the Disco. Directed by Tina Landau. Choreography, Christopher Gattelli; additional music, Tom Kitt; sets and costumes, David Zinn; lighting, Kevin Adams; projections, Peter Nigrini; sound, Walter Trarbach; hair, Charles G. LaPointe; makeup, Joe Dulude II; foley design, Mike Dobson; music direction, Julie McBride. With Wesley Taylor, Stephanie Hsu, Allan K. Washington, Kelvin Moon Loh, Gaelen Gilliland. About 2½ hours. $49-$250. At Palace Theatre, 1564 Broadway at 47th St., New York. Visit or call 866-448-7849

Once on This Island, book and lyrics by Lynn Ahrens, music by Stephen Flaherty. Directed by Michael Arden. Choreography, Camille A. Brown; music supervision, Chris Fenwick; set, Dane Laffrey; costumes, Clint Ramos; lighting, Jules Fisher and Peggy Eisenhauer; sound, Peter Hylenski; orchestrations, AnnMarie Milazzo and Michael Starobin. With Phillip Boykin, Merle Dandridge, Emerson Davis, Kenita R. Miller, Mia Williamson. About 90 minutes. $99.50-$249.50. At Circle in the Square, 235 W. 50th St., New York. Visit TeleCharge or call 212-239-6200.