Three-year-old Theo Evans rode atop his father’s shoulders Wednesday night, the duo wandering the New England Aquarium together like explorers. Among the exhibits, they discovered sea turtles and leafy sea dragons, sea horses, crabs, and sea stars.
That evening, the aquarium was their playground.
“Can you smell it? That’s the penguins,” said Meghan-Elizabeth Foster, senior educator at the New England Aquarium.
“I smell it,” Theo said, wrinkling his nose at the fishy odor.
The toddler’s family was one of three participating in a private, behind-the-scenes tour of the aquarium, labs, and medical center as part of the Sea Exploration and Adventure Star program. Theo and two other participants are patients at MassGeneral Hospital for Children.
Doctors diagnosed Theo with cancer on Good Friday nine months ago.
To Theo’s parents, Erik and Amanda Evans, life these days is measured in doctors’ appointments and treatments that bring them from Vancouver to Boston with their son.
First chemo treatment. Second chemo treatment. Radiation is now fewer than 10 days away, which means a monthlong stay for mom and dad at the Ronald McDonald House in Charlestown.
But Wednesday night as the sun set over Boston Harbor, the boy in the blue Nikes and Santa Claus socks met a Southern Rockhopper penguin named Falkland, saw a whale tooth taller than his dad, and learned about whale poop. He dubbed a baby lobster Raphael after the Ninja Turtle, and got to touch sharks and stingrays.
“He doesn’t understand the gravity of what he’s going through,” said his dad. “It’s so nice that he enjoys stuff like this and not think of the other stuff heavy stuff hanging over.”
Staffers told their pediatric visitors that the sea creatures act differently at night, perhaps a bit calmer after a hectic day.
“One of my favorite things about working at the aquarium in general is seeing families have fun together,” Foster said, “just look at an animal or look at a habitat or one of our exhibits, and get excited and ideally ask questions together.”
Slender seahorses normally hidden beneath coral swam out. Isis the African penguin cuddled closer to her partner, Seneca. Colorful fish swirled in schools, while a giant sea turtle chomped on its lettuce dinner.
Volunteers invited the group to the aquarium medical center.
They didn’t use the h-word: hospital.
“It’s like the doctor’s house, but for the fish,” Theo’s dad told him. “Let’s check it out.”
The patients inside were two fish that were going to be transferred to the South Carolina Aquarium in Charleston the next day. There was a stuffed penguin and stuffed fish to show the kids how doctors take x-rays or do surgery on sea animals, if necessary.
Kerry McNally, senior biologist in the animal health department, said: “They can see our patients, the kind of procedures we do, and sometimes can relate a lot to it.”
At every exhibit, Allison Vilms stuck by her friend, McKenna Lappin. Vilms visited Lappin in the hospital nearly every day last month.
Doctors still don’t know what caused Lappin’s stomach pains and blood clots. Finally discharged before Christmas, her parents give her two injections a day.
The girls, both seventh graders at Dexter Southfield School in Brookline, laughed and squealed as they watched the electric eel hunt down worms in its tank.
“It’s amazing,” said Mara Lappin, McKenna’s mom, about the aquarium experience. “The care doesn’t stop once you get discharged.”
Joshua Fauvel, at 15, the oldest of those invited on the SEA Star visit, split his time between touring the aquarium and keeping on eye on his younger siblings. He wandered with his mother, Katie Dean, 33.
The Georgetown family take Josh to MGH for inpatient chemo treatments every other week. He was diagnosed with Ewing Sarcoma last September.
The teenager said he listens to music or watches “Fuller House” on Netflix during treatment, to take his mind off where he is.
“Everything is just day by day,” Dean said. “He was really excited and loves coming here.”
It was a night to forget about hospital rooms and prodding needles. It was an opportunity to appreciate how far they’d come, to be present and be together. It continued into the evening.
After dinner, Theo got his favorite: vanilla ice cream.
“While there’s so much darkness and the worst in life is what we’re experiencing, a lot of good comes from that,” Erik Evans said, “and that’s really nice. All the kindness and positivity that comes from such a negative nightmare situation. It’s pretty amazing.”
Cristela Guerra can be reached at Cristela.Guerra@globe.com.