An impromptu visit from Captain Jack Sparrow was a surprise treasure for some young cancer patients.

Actor Johnny Depp, who was in Spain for the San Sebastian Film Festival, dressed as the famous character from the popular "Pirates of the Caribbean" film series and dropped into the Osakidetza Donostia University Hospital.

Depp visited the pediatric and oncology wards, where he interacted with the delighted children and their families.

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A spokesperson from the hospital described the actor’s visit as "exciting, endearing and unforgettable."

Depp visited the pediatric and oncology wards, where he interacted with the delighted children and their families. (Osakidetza Donostia University Hospital /TMX)

"Both the children admitted to the hospital and their families and professionals who were working at that time welcomed him with great enthusiasm and affection," the spokesperson said. 

"In a situation of illness, anyone, but especially children, greatly appreciates a distraction of this magnitude. It was a breath of fresh air, a magical moment in which they forgot about their illness and were transported to the magical world of pirates."

A spokesperson from the hospital described the actor’s visit as "exciting, endearing and unforgettable." (Osakidetza Donostia University Hospital /TMX)

The entire hospital team, the admitted children and their families are all "enormously grateful" for Depp’s visit, the spokesperson said. 

"It has been a pleasure and an honor to have Jack Sparrow with us, a great pirate."

‘Meaningful impact’

Harpreet Pall, MD, chair of pediatrics at K. Hovnanian Children’s Hospital at Hackensack Meridian Jersey Shore University Medical Center, confirmed that a celebrity role model visiting a children’s hospital can have a "meaningful impact" on the patients’ emotional health.

"Some of the psychological benefits include improved self-esteem and confidence, distraction from illness, improved optimism and a morale boost," Pall told Fox News Digital. 

Actor Johnny Depp arrives for the world premiere of "Pirates of the Caribbean: Dead Men Tell No Tales" in Shanghai on May 11, 2017. (Getty Images)

"A celebrity visit can create excitement and decrease some of the stress of being in the hospital."

The visit can also increase children’s engagement with their health care team, the doctor said, leading to better adherence to the treatment plan. 

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Pall added, "In addition, having a positive outlook and social interaction promotes healing for hospitalized children."