Underwater Farm Grows Basil, Tomatoes, Strawberries

A diver wanted to test an idea for growing a garden inside a transparent balloon – in the ocean.

Under The Ocean

A recent article published by Atlas Obscura profiled Sergio Gamberini, a professional scuba diver and amateur gardener in northwest Italy who wanted to test an idea for growing a vegetable garden inside a transparent balloon – in the ocean. Dubbed Nemo’s Garden, his curiosity now encompasses six underwater greenhouses hosting an estimated 700 plants.

His crops include basil, tomatoes, strawberries, aloe vera, mint and marjoram. Although a great deal of validation is still needed, it's hoped that this approach to farming could be utilized in areas where crop-growing conditions are less than ideal. 

One of the biggest challenges was complying with an Italian law that makes it illegal to permanently change the seafloor. So the underwater greenhouses had to be removable but strong enough to withstand storms. The answer has been the use of rigid plexiglass with an internal and external steel skeleton. The semi-spheres are six feet wide, three feet high, and attached to the seafloor with 28 removable screws. So far this design has provided the right combination of stability and compliance.

The next obstacle was getting the right amount of sunlight, fresh water and oxygen to the plants. Fontanesi estimates that the underwater plants get about 30 percent less sunlight than those on the surface. So this is supplemented by artificial light from LED lamps placed inside the spheres. These lights and an irrigation system are powered by electricity from solar panels and a small wind turbine onshore. Although a series of tubes currently carries water to the plants, the long-term plan calls for a natural desalination process.

The semi-spherical design means the bottom of the plexiglass housing is open, but doesn't flood due to the same principles that apply to a submerged glass or bottle. Air pressure ensures that water only fills the bottom part of the biosphere.

One of the most interesting takeaways from early testing on the produce turned out by Nemo's Garden has been a unique distribution of certain chemicals. For example, basil plants have shown higher concentrations of eugenol (a substance contained in basil essential oils) and more chlorophyll compared with plants grown on land. Although more testing will be needed, this could translate to more potent plants used for medicinal purposes.