What Would It Take to Build a Permanent Underwater Colony?

The current state of the environment has led people to consider moving to space, but what about the ocean? While it remains largely unexplored, ocean colonization may be more tangible than living on a foreign planet or a massive spacecraft. However, it would present many challenges, such as pressure, life support, power, psychological impacts and ongoing maintenance that scientists have not prepared their current technology for.

Why Humans Consider Living Underwater

The liveable environment for humans is on a steady decline. Scientists predict that greenhouse gas emissions will increase by 75 billion tons by 2050. Without significant changes, the Earth will become hotter and more polluted. Many species will also go extinct. The ocean’s temperature is even rising, damaging ecosystems and disrupting the migration of organisms. It may still be habitable, but the predicted living conditions are convincing people to explore space or establish underwater habitats.

Hurdles When Building an Underwater Habitat

An underwater habitat must be able to handle the pressure, lack of oxygen, need for energy, psychological impact on humans and ongoing maintenance to create a sustainable colony.

Immense Pressure

Humans experience hydrostatic pressure as they swim deeper in the ocean. The weight of gravity bears down on their backs as water piles on top of them. This is a problem for underwater habitats because the materials used for structures must withstand that pressure. Carbon fiber composites can handle some of it. Scientists already use titanium alloys for deep-sea exploration because they can resist corrosion. Transparent ceramics are as strong as crystals but still flexible enough to bend into functional shapes. 

While these are viable options, more research, field tests and technological developments are necessary to see if these materials will prove effective in an underwater habitat.

Life Support

Humans need oxygen to live, so ocean colonies must find a way to provide breathable air. The key is to build a self-sustaining atmosphere that creates oxygen on its own. For example, scientists have used electrolysis to generate oxygen. Also, carbon dioxide (CO2) scrubbers remove the gas from the air, preventing people from suffocating. These methods will need further development to be sustainable for an entire underwater colony.

Submarines use CO2 scrubbing, as well as bottled oxygen and carbon monoxide and hydrogen burners to create breathable air. The International Space Station (ISS) converts 50% of the CO2 produced by astronauts into oxygen. Scientists must further develop these methods to find an ideal solution for underwater habitats.

Beyond air, humans will also need food. Without soil, they can use advanced hydroponics to grow plants. This process requires water and liquid fertilizers, along with environmental controls, to create ideal conditions for growing food, such as fruit or vegetables. Residents of the underwater colony could practice aquaculture by breeding and harvesting sea animals and plants for food as well. 

Power Source

Ocean habitats will need a viable power source for an extended period. One option is to run an umbilical cord from the surface down to the colony, but external factors could damage the cord, or the air above could become unusable. Small modular reactors (SMRs) are a small-scale nuclear power option. A renewable energy method, ocean thermal energy conversion, uses the thermal gradient between warm and cold seawater to power a heat engine. All of these possibilities require significant further research before implementation.

Psychological Impact

Humans may not respond well to living underwater. Intense isolation and confinement create lasting psychological effects. For example, solitary confinement in prisons causes inmates to have hallucinations, anxiety, depression and an increased tendency for self-harm. The lack of natural light underwater would damage people’s sleep schedules, exacerbate moodiness and cause depression.

The body also changes under immense pressure, sometimes causing muscles and tendons to experience shifts. Pressure can cause pain, stiffness and issues with the brain. The artificial atmosphere of the ocean colony may negatively impact people’s psyches, as space does. Astronauts experience many symptoms, such as gravity-related issues, dietary changes and bone irregularities, after extended missions. The possibility of what could happen to the body after living in the sea forever concerns scientists and explorers.

Ongoing Maintenance

A final hurdle for living underwater is ongoing maintenance. Water can deteriorate materials over time, even strong ones, so regular replacements of various structures will be necessary. Humans cannot venture outside and fix leaks or other damage the way astronauts sometimes do on the ISS. The colony’s citizens would need robots for external repairs and construction, such as autonomous underwater and remotely operated vehicles. These also reduce the human risk if they were to go outside to perform maintenance. 

Why Oceans Remain Largely Unexplored

Space is not the only option for a new human colony, but there is less knowledge about the sea as an alternative. In fact, around 80% of the ocean is still unmapped. One reason is the intense pressure. Engineers are creating machines that can withstand increasing pressure, but the technology is not advanced enough to support super-deep exploratory missions.

The temperature is another concern. The deeper the water, the colder the temperature. The Hadalpelagic Zone is the lowest part of the ocean, extending to the bottom of the Mariana Trench. Its temperatures are typically a little above freezing. People risk their well-being before reaching the bottom, and equipment can lose signals and computing power. 

While space’s size is clearly visible thanks to many high-definition photos, people often forget that the ocean’s size is not just the surface, but thousands of meters below. While explorers have sailed the length of the ocean, they have yet to discover all that lies at the bottom. It is an immense region, so finding a suitable place to set up a colony is much harder.

Promising Technology Could Make it Possible

Building an underwater habitat will be difficult, but today’s technology remains promising. If environmental pressures worsen, then an ocean or space colony may become more realistic. Still, some scientists consider an ocean colony more tangible than a space one. Time will tell which one prevails.