When Boyan Slat was 16 years old, he decided to try to save the ocean.

"I've always been making stuff," Slat said. Now he's 21, a young man with full hair, and he says he's been an inventor since he was young. He built tree houses and ziplines in his native Netherlands as a child. And once, when he was 12, he decided to see what would happen if he launched 250 model rockets at the same time.

"I liked problem-solving, but what I didn't really have was a real problem to work on."