Set to start operating this fall, the farm will cover 5 hectares (12.4 acres) and is expected to produce at least 6,000 kilograms (13,227 pounds) of fresh seaweed in its first year.

For the past year, 14-year-old Jeremy Yang and his peers from The Harbour School have been working on what might be one of Hong Kong’s most unique school projects: building seaweed farms along ...