Silver-Vallance's escapade adds to the lore of an island that served as a prison under Dutch settlers in the 17th century. At that time, a jailed local leader escaped to the mainland. In 1819, a Xhosa chief who opposed colonial rule drowned after trying to escape.
Lepers also stayed on the island and one group built a boat to flee but authorities discovered and destroyed it, according to Khangala, the spokesman at the island museum.
Vuyo Lutseke, spokeswoman for the Nelson Mandela Children's Hospital, said one-quarter of $110 million needed to build the hospital in Johannesburg has been raised and that organizers hope to start construction around Mandela's July 18 birthday.
"We're very optimistic, but we also understand that we need the larger global community to come on board and help us in raising this money," said Lutseke, who welcomed what she described as Silver-Vallance's "crazy" stunt. The balloonist is raising money through online donations, and the independent trust running the hospital project will decide how best to spend the funds.
Mandela, who last made a public appearance in 2010, was known for a lively sense of humor during his career.
"He seemed to be the kind of individual who was able to mix humor with the serious nature of everything that he was doing," Silver-Vallance said. "We all hope, if he sees this story, that it will bring a smile to his face."
Robben Island Balloon Run: http://www.balloonrun.com/
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