For over a thousand years, the port of Lamu, Kenya, traded with the world. Merchant ships would arrive, dock near the city’s minarets and palm trees, and leave carrying ivory, mangrove wood and slaves. Then, a century ago, the old trade began to decline, before being gradually replaced by a new one: tourism. Growing up in Lamu, Mansoor, now 31, watched as visitors arrived with money and left behind their trash. Then, one day, he was looking at the discarded plastic along the shoreline and had a revelation: this was a resource, and with it, he would build something everyone in Lamu needed. He would build a boat.