Nickelodeon hopes 'Diego' rivals 'Dora'

To research her latest children's television project, producer Valerie Walsh went on a hair-raising business trip to Peru last year.

After visiting animal-rescue centers in the jungle, she would retire under giant mosquito nets in makeshift hut-style hotels. There was no glass in the windows, no electricity, and no hot showers. There were, however, the sounds of animals howling and scampering outside.

''I like to look at it as: I survived," she says.

Walsh was on a quest to gather authentic story lines for the animated series ''Go, Diego, Go!," a spinoff of Nickelodeon's blockbuster hit ''Dora the Explorer," which has been the No. 1 preschooler series for four years.

''Go, Diego, Go!" premieres tomorrow at 8 p.m. on Nickelodeon and then moves to its regular time, weekdays at 11 a.m., beginning Wednesday.

The series will feature Diego, Dora's 8-year-old cousin, who was introduced on that program two years ago.

Diego is a bilingual Latin-American boy living in a rain forest in South America, where his scientist parents operate an animal-rescue center. A nature lover himself, Diego -- who has the ability to converse with animals as well as speak English and Spanish -- will spend each episode rescuing animals in scenarios Walsh heard about during her visit. One day, for example, a sloth will be caught in a river's current. Another day, a llama will be trapped in a pool of mud.

''One animal rescuer told us that he found a sloth caught in a river during a rainstorm," she says. ''The sloth couldn't swim out because it moves very slow and the river was moving fast. So the rescuer gave the sloth a piggy-back ride to shore. That totally inspired us."

Diego will be joined by a host of other characters, including his 11-year-old sister, Alicia, his pet, Baby Jaguar, a pair of mischievous spider monkeys called the Bobo Brothers, a messenger bag called Rescue Pack that can transform into modes of transportation, and a camera, Click, that helps him find his way through the forest.

The new series is launching at a time when the young children's television market is already packed with competition.

Disney Channel has ''Stanley," a program about a little boy who likes to explore the animal world. Noggin, which is owned by Nickelodeon, has ''64 Zoo Lane," a series about a little girl who lives next door to a zoo. PBS has ''Maya & Miguel," a show chronicling the adventures of a set of 10-year-old twins who often converse in Spanish. ''Dora," of course, is also still going strong. Its licensed merchandise, which includes more than 100 products, has brought in $3 billion in retail sales since 2001.

Peggy Charren, a children's television activist, wonders why Nickelodeon didn't develop a series about a different culture and ethnicity. ''It certainly doesn't hurt to have another Hispanic hero in programming. We've gone for years without any," she said. ''But we also need to see more of other cultures."

Brown Johnson, executive creative director of Nickelodeon's preschool television, says that other series are pending but rich characters like Diego are more important in program development than ''checking the box of a race."

Two years ago, the network approached Walsh, who co-created ''Dora" with Chris Gifford, about producing a spinoff that would appeal to the same audience, 2- to 5-year-olds. ''We've made 100 episodes of 'Dora' since 2000, which seems like a lot," says Johnson. ''I don't know if we'll duplicate a monster hit . . . but I think it's smart to look for new avenues of creativity in any long-standing series."

Taking note of the reported shortage of children pursuing careers in science, Walsh and Gifford inserted scientific tools into the show in hopes of sparking some interest. ''Diego is going to use tools like a magnifying glass and binoculars to solve problems," Walsh says. ''His world will be less fantastical than Dora's. You won't find a chocolate lake, for example. You will find animals indigenous to Latin America."

Walsh and Gifford's trip to gather material at animal-rescue centers in Ecuador and Peru was no vacation. ''We were woken up at 4 a.m. and we fell into bed at 10 p.m.," she recalls.

What they came away with was the conviction that no plotline was too outrageous. ''We were going up a mountain and a boulder was blocking the road," she recalls. ''They had to get seven men from town to move it. That really helped us in our writing. When someone says, 'That's not realistic,' we know it is."

The producers auditioned 30 boys to voice Diego before settling on Jake Toranzo-Szymanski, a 10-year-old New York resident who is Puerto Rican, Argentine, and Polish.

''I came in with a great idea of how Diego should sound . . . very energetic but slow," he says. ''With little kids, you have to slow it down."

Toranzo-Szymanski says he had a hard time convincing his 3-year-old sister, Eva, that he was going to replace the previous Diego actor, who was let go because his voice had changed.

''I said, 'Eva, I'm Diego,' " Toranzo-Szymanski says. ''She said, 'No you're not.' . . . I think she's gonna freak out when the show comes on with my voice and I'm at school."

For her part, Walsh is glad to be back to her bicoastal living in Manhattan and Los Angeles. ''I'm low-maintenance in the city," she says. ''In the jungle? Forget it."

Suzanne Ryan can be reached at sryan@globe.com.