It was dangerous not only because of the long distance. There were sharks in the waters, too. The woman had no protection. She had no shark cage and so she was the first person to swim from Cuba to Florida without one.
After she got on the beach in Florida, people gave her a warm welcome. The woman tried to swim this distance before but she didn't succeed. But this time she did and people were as happy just as much as she was.
Difficult words: shark cage (cage that protects you from sharks), succeed (do something successfully).
You can read the original story and watch the video in the Level 3