In Simple Terms
Four people spent five days living and working in a small underwater station without going back to the surface. They did research, shared a tight space, and relied on equipment to supply air, water, and power. Their experience offered a practical way to explore some challenges people might face on long journeys far from Earth.
An Underwater Station That Felt Like Another World
Life deep beneath the sea is not always noisy or chaotic. The crew of the SEA STAR mission described their days inside Jules’ Undersea Lodge as surprisingly calm. But that quiet came with an inescapable reality: four people were sharing a confined space about 22 feet (roughly 7 meters) below the surface, hearing little from outside except the sounds of the life-support systems. This was not a spaceflight, but it gave the team a chance to experience isolation and daily work in a demanding environment—conditions that could matter when planning long human missions beyond Earth.
Jules’ Undersea Lodge sits near Key Largo, Florida. When it was established in the 1970s, it was known as La Chalupa. The facility was designed as a place where divers could live and work underwater, rather than simply as a way to descend below the surface for a short time. People who stay underwater for more than 24 hours are known as aquanauts, a name that reflects their extended time in a marine environment under the pressure of the surrounding water.
The station was not originally tied to one location. It was built inside a barge 20 feet wide and 60 feet long—about 6 meters wide and 18 meters long. Its location could be selected to suit a mission, and the structure could then be lowered into place. To turn the floating barge into a submerged habitat, most of its interior was filled with water. When a mission ended, the water was pumped out so the structure could be moved again.
Funding to operate the facility eventually dried up, and it was moved for the last time to its current location. Since then, it has served as a research station for dozens of missions involving aquanauts. Those efforts have included a 30-day NASA project, as well as two missions that set records for underwater stays: one lasted 73 days and the other 100 days. These earlier missions show that the station is more than a setting for a brief experiment. It has been used to test what it takes to live and work in marine isolation for varying lengths of time.
Entering Through the Moon Pool
The station’s entrance is not an ordinary door opening onto a dry hallway. People enter and leave through an opening called a moon pool, which serves as a passage between the water and the habitat. At the start of the SEA STAR mission, the crew said goodbye to the mission-control team, which represented Earth, then dove down to reach the station through the opening. The mission account says they entered at a depth of 25 feet, or about 7.6 meters, while the habitat itself is described as being around 22 feet, or 7 meters, below the surface.
Once inside, the crew did not return to the surface until the five days were over. They lived and worked in the station, carried out space-related research, and undertook what they called simulated spacewalks: exploratory dives using scuba gear. The distinction is obvious, of course. These activities took place in water, on Earth, not in the vacuum of space. Still, the team had to follow a confined daily routine in an enclosed setting, echoing some demands of space missions.
The habitat includes an area for cooking, eating, and working, along with a basic toilet and shower. A sleeping room has two bunk beds, and it can be divided into two rooms to provide a little more privacy. Three windows look out onto an underwater scene dominated by green. Small domestic details matter when the habitat becomes the crew’s entire world for a time. The challenge is not just carrying out experiments; it is also sleeping, eating, keeping clean, and working in the same limited space.
Life Depends on Support Systems—and Staying in Touch
The crew depended on more than the station’s walls to stay underwater. The facility relied on life-support systems and supplies delivered through cables and connecting lines, which provided air, fresh water, and power, as well as communications. NASA originally supplied the connections and support equipment. Pipes and cables run through the submerged barge, where they are protected from the boundary between the air and seawater and from marine organisms that can attach to surfaces and cover them.
Along with the supply lines, the crew had a direct channel to mission control on Earth for use in an emergency. This makes clear that simulating isolation does not mean cutting off every link to the outside world. Communication and backup support are essential parts of operating the habitat. The crew can spend days away from the surface, but staying alive depends on external equipment, monitoring, and the ability to ask for help when needed.
This is where the underwater lab differs from the image of complete isolation that people might imagine. The four crew members were cut off from their usual lives on land, but they were not without technical support. Air, water, power, and communication were not minor details of the experiment; they were the conditions that made the stay possible. At the same time, relying on systems connected to the habitat meant that checking equipment, maintaining it, and responding to unexpected problems were part of the crew’s daily work—not tasks that could simply wait until the mission was over.
A Busy Schedule in a Tight Space
The SEA STAR crew had four members, each responsible for a research project as well as shared daily duties. Their tasks included preparing food, conducting medical checks and cognitive tests, maintaining the station, and dealing with unexpected issues. Mission commander Michaela Musilova, an astrobiologist and explorer, kept track of the crew’s work and helped resolve problems as they arose.
The structured routine was intentional. The mission aimed to reproduce some aspects of life aboard the International Space Station, where scientific experiments happen alongside looking after the crew’s health and equipment and handling the demands of everyday life. This was not an exact replica of life in orbit. It did, however, let the team test what happens when a small group must coordinate work, rest, and duties in a confined place, keep to a schedule, and cannot simply leave its surroundings.
Among the crew’s other duties were exploratory dives that stood in for spacewalks. The dives were physically tiring, so the team did not add other workouts to its schedule. Musilova, who has led 40 space-simulation missions, says training on the missions she has taken part in typically included an hour or two of exercise each day, much like the routine followed by International Space Station astronauts. Conditions at Jules’ Undersea Lodge were different: the pressure there was close to twice that at sea level, placing extra strain on the crew’s bodies. As a result, they skipped additional exercise during this mission.
The comparison shows why it is important to consider the details of an environment, not just the broad outline of an experiment. Working underwater and living in space may seem completely different, yet both can involve a tightly managed schedule, equipment that must be monitored, and tasks that demand ongoing cooperation. But similarities in routine do not mean that pressure, movement, or risks are the same. The underwater mission had its own conditions, including the high pressure that led the team to adjust its exercise plan.
Small Comforts That Lift Spirits
Despite days packed with duties, the crew did not feel they were under unusual psychological stress, according to Musilova. She could not say for sure why. Careful planning may have helped, and perhaps the confined conditions of the experiment played some part. What mattered was that the crew found that routine and shared work helped them keep going—and that living underwater was more enjoyable than someone looking in from outside might expect.
Food brought some welcome surprises, too. The crew was allowed to use a small cooking pot, which meant they could make soup, stews, and overnight oats. These foods are not scientific equipment, but they are part of the practical reality of living in a place where people cannot choose to have a spacious kitchen or go out and buy whatever they want. A familiar or warm meal can make the day feel a little more like home and soften the strangeness of life in a habitat surrounded by water.
The experience is a reminder that preparing for a distant mission is not only about equipment and measurements. It also means considering the conditions that help people live and work together. Limited privacy, shared responsibilities, managing time, and finding moments of comfort all shaped the crew’s everyday life. Five days alone cannot show how people would cope with a long journey to Mars, but the mission offered a real-world test of how a small group handles a confined place and an unfamiliar environment.
Why Did the Ocean Feel Like Mars?
The similarity Musilova described was not that the seafloor looked geographically like the surface of Mars, or that underwater pressure matched conditions in space. She was talking about a feeling created by the way of life: being separated from everyday life on Earth, relying on a limited habitat, and facing an environment outside the windows that looked unlike the familiar world. The green underwater view made the crew feel as though they were looking out at a strange place, even though it was neither a desert nor another planet.
The daily routine gave life a steady rhythm, while the demanding environment kept the crew alert. Their research and exploration also gave them a clear purpose. In the mission commander’s view, that mix of familiar structure and unfamiliar surroundings was what made the experience feel Mars-like. Living far from Earth could bring social, psychological, and practical challenges as well as technical ones. Simulated environments can therefore help researchers study how a crew works when a confined habitat becomes the center of their lives for a while.
Even so, a simulation is a tool for training and learning, not a substitute for an actual space mission. In the underwater lab, air, water, and power could be supplied through support lines, and the crew could still contact mission control. Space travel involves different conditions, and an underwater experiment cannot reveal every detail of what it will be like. SEA STAR’s value lies in giving a crew the chance to test coordination, routines, and life in relative isolation in a genuinely challenging environment—and in helping raise practical questions about what people need when they leave their familiar surroundings.
The Bottom Line
The SEA STAR mission combined an underwater stay with research relevant to space exploration. Four people spent five days in Jules’ Undersea Lodge near Key Largo without returning to the surface. They entered through a moon pool and lived in a habitat supplied with air, water, and power, with an emergency communication channel to mission control. Their days included research projects, medical checks, tests, maintenance, and tiring exploratory dives.
The stay was short compared with earlier missions at the station, including a 30-day NASA project and two stays lasting 73 and 100 days. But it showed how an underwater facility can provide a tangible setting for testing some parts of life in isolation: organizing time, working as a team, managing equipment, and finding ways to maintain morale. The ocean did not make the crew live on another planet, but it offered a practical glimpse of challenges that could accompany people on distant journeys—and showed why the details of everyday life matter alongside big scientific goals.