Once upon a time, there was a man named Thor Heyerdahl. He was a big adventurer, which means he liked to travel and explore new things. Thor was very curious about how people in the past lived and traveled around the world. He had an idea that people from a long time ago could have traveled across the ocean in boats, even if they didn't have high-tech instruments like we do now.
Thor wanted to prove his theory, so he decided to build his own boat to show that it was possible. He called his boat the Kon-Tiki, and he made it out of wood and rope just like people might have done a long time ago. Thor and his team set sail on the Kon-Tiki from South America, and they sailed all the way to Polynesia, which is really far away! Along the way, they encountered big waves and storms, but they didn't give up. They finally made it to their destination and proved that it was possible for people to have traveled across the ocean like that a long time ago.
Thor Heyerdahl became really famous for his adventure and his ideas about how people from long ago might have traveled around the world. People still talk about him and his Kon-Tiki adventure today.