5 days beneath the waves: What it's like to live in an underwater 'space station'

Living submerged beneath twenty feet of water feels surprisingly peaceful, offering a remarkably close simulation of what human life on Mars might one day entail. During a five-day mission called SEA STAR, a four-person crew locked themselves inside the Jules Undersea Lab off Key Largo to study the extreme physiological and psychological challenges astronauts face on long-duration space missions.

Originally built in the 1970s as a mobile, barge-based habitat called La Chalupa, the facility was designed to sink by flooding its inner chambers and rise again when relocated. After funding dwindled decades ago, it found a permanent home on the ocean floor, serving as a harsh training ground for numerous scientific crews, including a thirty-day NASA project and historic endurance missions.

Inside the submerged station, survival relies entirely on a network of vital life support systems, with power, fresh water, and air pumped down through umbilical cables originally supplied by NASA. The cramped layout features a basic galley, a shared bathroom, a moon pool serving as the underwater doorway, and a bedroom with bunk beds that can be split for privacy.

Unlike standard space simulations, the ambient pressure inside is roughly twice that of sea level, forcing the crew's bodies to process physical stress that renders extra exercise unnecessary.

Our read is that while outer space involves microgravity rather than crushing water pressure, the psychological confinement of staring out at an alien green seascape through three small windows forces the human brain to confront the exact brand of isolation future Mars explorers must endure.