And it's not meant to be a wilderness stroll.
"Our courses are designed to be difficult and to push every student to their limits," said Costa Rica Outward Bound's executive director, Jim Rowe, in a news release.
From the get-go, the program aimed to do that, the girls said.
They endured a long application process involving essays and multiple references. Acceptance into the program was no guarantee.
Once in, they had to fund their own tuition. Lynelle Holman, the girls' mother, said each trip cost about $2,000, but the Girl Scouts of Utah were willing to pick up 25 percent of the tab on account of their years of active involvement with Girl Scouts.
The younger sister, Shaniah, went on the Rainforest, River & Reef 14-day trek, which demanded a high level of physical achievement.
Alannah went on the scuba trip that had her diving daily into the ocean off the island of Solarte near the Caribbean archipelago of Bocas del Toro, Panama.
Both said as a result of the trip they gained greater perspective and appreciation for their first-world lifestyle.
Shaniah spent the majority of her trek hiking nearly 40 miles through a soggy rainforest. Almost every night, her group would stay with villagers who lived in the lush green world. She was amazed at their two-walled homes that provided no barrier from the elements.
She also observed the locals making all of their own food.
If they wanted a banana, they climbed a tree. A vegetable? They grew it. Chicken or pork? Neitherunless you want to raise, kill, clean and cook it.
Miles away, Alannah was living on a island with no plumbing, showers or, of course, technology.
She realized that worrying about showers and food was not important. What mattered was the friendships she was making and the maturity she was gaining, she said. "A lot of people throw away good experiences because of stupid little things."
Every night, Alannah slept out in the open on a concrete slab with a wooden porch. She, along with the group, prepared her own food and got creative making meals out of what they had, usually just rice and "weird fruit."
She spent the days earning her scuba diving certification, water skiing and exploring local areas. At one point she went diving over a shipwreck with a multitude of different-colored fish. "It was insane. They were just swimming everywhere," she said.
In addition to hiking, Shaniah went on a nearly 6,000-foot zipline canopy tour. She rappelled down a 60-foot waterfall and she went whitewater rafting. On that day she fell out of the raft twice, slid down a nature-made rock slide and spun in whirlpools.
Despite the intense physical challenges, the girls had an "unbelievable" experience.
Alannah said, "Oh, it was so worth it."