Imagine sailing out to sea to tend to your garden underwater. Or envision a world where large scale farming could be moved into the depths of the ocean.
In a project dubbed Nemo's Garden, a team of engineers at Ocean Reef Group, a family-run scuba diving business, are currently experimenting with such ideas. They're trialling an alternative agricultural method which involves growing terrestrial crops in the sea. Now in their third year running, they think their underwater "biospheres"—soft plastic bubbles filled with air—could eventually provide the key to sustainably cultivating crops.
"My dad (Sergio Gamberini, president of the company) has a passion for gardening, and he thought that the sea—this enormous dispenser of thermal energy—would always give constant temperature, especially during the summers," Luca Gamberini, marketing manager of Nemo's Garden, told me.
"Sea temperature doesn't drop, whereas air temperature is a lot less stable as air molecules exchange heat very easily. We're studying how to harness thermal energy to benefit the growth of our plants."
While the sea is warmed up slowly by the Sun, it also loses heat less quickly, allowing temperatures to remain constant throughout the year.
Sergio Gamberini initially came up with the idea of growing plants underwater while holidaying with his family three years ago.
The team has so far taken seven transparent biospheres to depths of 7-9 metres beneath the Bay of Noli in Savona, Italy. Each air-filled biosphere consists of a hydroponics microenvironment, a structure containing the plants, and an anchoring system that attaches the mini greenhouse firmly to the sea bed. Hydroponics is a method of growing plants in mineral nutrients in water instead of soil.
"We want to be able to present the world with an alternative agricultural solution that doesn't require soil or [fresh] water."
"We wanted the concept to be simple so that any diver could assemble the biosphere underwater," Sergio Gamberini told me. He explained that when the balloon is taken underwater, it is inflated with air from a tank. As the pressure inside the biosphere is the same as outside it, no water enters the top part of the balloon. This means that when scuba divers tend to their plants, they can swim underneath the biosphere and enter the part of the biosphere filled with air—so while the lower half of their body is submerged in water, the upper half is in the water-free part of the biosphere where the plants are.
As the seawater evaporates, the water vapour condenses along the interior wall of the biosphere, creating a humid environment with a plentiful source of fresh water for the plants. The ocean environment also shields the plants from the parasites and abrupt changes in climate they would be exposed to n land.
"Underwater, we don't have rats or other diseases that [the plants] could be susceptible to, and we definitely don't need pesticides," explained Luca Gamberini.
The group asserts that its biospheres are an "ecological and auto-sustainable system," and says that currently the main aim is to understand how the underwater environment affects different plants. To date, the team has prioritised experimenting with a variety of species over mass-producing one crop.
"We're growing everything that comes to your mind," Luca Gamberini told me, citing strawberries, lettuce, basil, tomatoes, and wild flowers as examples.
He said that Initial lab analyses of all the crops revealed no significant differences between plants grown on land and underwater. One small difference, however, was that the plants actually grew more quickly in the sea.
"We saw that the growth rate of what we planted increased, and we believe it's because the air inside the biosphere is more compressed," said Gamberini. He finds these preliminary findings promising, but said that they weren't enough to hold a press conference on just yet. The team expects to publicise more results in October.
Nemo's Garden eventually wants to work soil out of the agricultural equation. "We want to be able to present the world with an alternative agricultural solution that doesn't require soil or [fresh] water," said Gamberini. He cited equatorial regions as having a dearth of suitable water and soil, explaining that "these harsh conditions really inhibit the growth of plants."
As well as dreaming of helping to alleviate the world's pressing agricultural demands, Gamberini sees the underwater greenhouses as simply a place of wonder.
"I saw the interactions between two worlds that are naturally separated by evolution with my own eyes [...] As soon as we plant some structure inside the ocean, some creatures immediately inhabit it," said Gamberini, giving seahorses as an example.
While it's not possible to cultivate your own Nemo's Garden just yet, curious onlookers can gain an insight into the scuba diving gardeners' activities through live stream videos. Humidity and air temperature updates from inside the biospheres are also monitored and provided on the team's webpage.
The team wants to get more researchers involved, and eventually allow the public to own and tend their own biospheres.
"It's beautiful to be underwater because it's kind of like an inverted aquarium," said Gamberini. "Whenever you are working inside Nemo's Garden, it actually feels like you are in the aquarium and the sea creatures are watching you from outside."
Hell or Salt Water is a series on Motherboard about exploring and preserving our oceans. Follow along here.