Ocean farming is not a modern innovation. For thousands of years cultures as diverse as the ancient Egyptians, Romans, Aztecs, and Chinese have farmed finfish, shellfish, and aquatic plants. Atlantic salmon have been farmed in Scotland since the early 1600s; seaweed was a staple food for American settlers.

Unfortunately, what was once a sustainable fishery has been modernized into large-scale industrial-style farming. Modeled on land-based factory livestock farms, aquaculture operations are infamous for their low-quality, tasteless fish pumped full of antibiotics and polluting local waterways. According to a recent New York Times editorial, aquaculture "has repeated too many of the mistakes of industrial farming -- including the shrinking of genetic diversity, a disregard for conservation, and the global spread of intensive farming methods before their consequences are completely understood."

Unsurprisingly, once information got out among the general public, "aquaculture" quickly became a dirty word. Industry responded with a strategy of mislabeling seafood and upping their marketing budgets, rather than investing in more sustainable and environmentally benign farming techniques.

But a small group of ocean farmers and scientists decided to chart a different course. Rather than relying on mono-aquaculture operations, these new ocean farms are pioneering muti-tropic and sea-vegetable aquaculture, whereby ocean farmers grow abundant, high-quality seafood while improving, rather than damaging, the environment.

One example is Ocean Approved in Maine, which cultivates seaweed that doubles as a nutrient-rich food source and a sponge for organic pollutants. Farmers in Long Island Sound are exploring diversifying small-scale organic shellfish farms with various species of seaweed to filter out the pollutants, mitigate oxygen depletion, and develop a sustainable source for fertilizer and fish meal. In southern Spain Veta La Palma designed its farm to restore wetlands, and in the process created the largest bird sanctuary in Spain, with over 220 species of birds.

Seaweed farms alone have the capacity to grow massive amounts of nutrient-rich food. Professor Ronald Osinga at Wageningen University in the Netherlands has calculated that a global network of "sea-vegetable" farms totaling 180,000 square kilometers -- roughly the size of Washington state -- could provide enough protein for the entire world population.

The goal, according to chef Dan Barber -- named one of the world's most influential people by Time and a hero of the organic food movement -- is to create a world where "farms restore instead of deplete" and allow "every community to feed itself."

But here is the real kicker: Because they require no fresh water, no deforestation, and no fertilizer -- all significant downsides to land-based farming -- these ocean farms promise to be more sustainable than even the most environmentally-sensitive traditional farms.