I just past hour 170 of my dive, definitely the longest dive I’ve logged so far, so today I figured I would give you guys a tour of the habitat and let you know a little bit about the somewhat surreal life underwater. As I said earlier, the habitat is anchored on the bottom, midway down the fore-reef wall on Conch Reef. The reef is around 60’/20m here and the habitat sits up off the bottom, so our living depth is ~50’ (16m). This gives me 6 hours a day working at my deep sites. I can make a four hour excursion, spend 4 hours in the habitat at what we call “storage depth” to off-gas, and then make another 2 hour excursion. Because dive computers don’t work down here (They start freaking out around 24 hours and by 36 hours I think they just assume you’re dead and quit) we have to dive square tables, which limits our bottom time quite a bit, but still blows-away anything we could do surface-diving. To maximize our bottom time, each rig is equipped with a fill-whip, which is basically a high-pressure hose connected to the first stage of the regulator that we can plug in to refill our cylinders. This means we can refill without ever having to get out of the water or even take off our gear. We can fill at the habitat, and the Aquarius crew also sets up way-stations with gas – basically little gazebo’s with an air pocket and gas control panel inside and so you don’t have to go all the way back to the habitat to refill.
When we’re in the habitat there isn’t a whole lot to do, which is okay because we’re usually pretty exhausted and have plenty of data to enter and equipment to prep for the next dive. The habitat itself is about the size of a city bus, with equipment and shelves on each side of an aisle running down the middle.
All six of us sleep in the bow on bunks, which sounds crowded but I hardly notice with everything else going on. Between the slight swaying of the habitat, the cacophony of snapping shrimp and fish scraping food off the hull, and the silhouettes of fish darting around outside the window I’m usually out within 10 minutes.
The main cabin consists of a small table, our “galley” (sink and microwave) and the main control bench for the habitat. It’s the area where we spend most of our down time, sitting around snacking and watching the fish out the window. Breakfast, lunch and dinner are all freeze-dried meals (Mountain House for all you campers) which aren’t too bad, and lots of candy to graze on during down time. We also have a cold box stocked full of cheese and a stockpile of coffee and hot chocolate, which are essential when you get back into the chilly habitat after 4 hours at depth. The AC is running constantly to keep the condensation down and humidity is always around 75% in the main hold so you always feel damp and cold.
The second compartment has a redundant control panel for the habitat and space for science equipment. We have a few instruments deployed to track water chemistry 24-7 as well as imaging sonar to monitor fish behavior that fill up most of this space. The main pressure door to the habitat that will be sealed when we start decompression is here as well.
Just outside the main lock is the wet porch, a room welded onto the outside of the habitat that’s maintained as an air-pocket without any actual pressure control. The wet porch houses most of the control panels for the exterior hoses, our shower and dive gear. This is also our entrance to the reef. All we have to do is step down into the moon pool, put on our gear and we can duck under the wall and swim out onto the reef.
The habitat is connected by an umbilical to a life support buoy (LSB) on the surface. The LSB holds all our fresh water and has two diesel generators and compressors that pump down air maintain pressure in the habitat. In addition, this is where we get all our power (and the wireless internet signal).
All our equipment and food gets carried down to us in “pots” which basically look like large pressure cookers that are sealed to keep everything dry. The surface support team pots down all of our food and science equipment before the mission starts. Then periodically makes visits to restock anything we may be low on and pot garbage back up for disposal. Any work down here takes a bit of extra planning because almost nothing is designed to work at depth. For example, all of the computers for data collection need solid state hard drives because the pressure pushes the discs together and locks up traditional hard drives. Buttons on electronics and pressure sensitive touch pads get stuck down and don’t work, and food containers typically get a small hole punched in them to prevent the entire container from collapsing. Even diving equipment requires some forethought. For example camera housings need to be left open and potted down or we can’t get them open once we’re at depth.
Our biggest concern in the habitat isn’t flooding, but is actually fire. Although the percentage of air in the atmosphere remains the same, because of the pressure there is more oxygen present, so small sparks and electrical shorts can quickly start fires. Flooding is also a concern, but ranks below fire and toxic gasses. If we lose power we can seal the habitat and have enough air for the six of us to last 72 hours. Additional storage bottles outside the habitat can provide another 3 days of air so if needed we could make it nearly a full week without power. In the event of a fire, chemical spill or flooding we can evacuate through the wet porch in the stern or an escape hatch underneath the bunks in the bow. Each location is stocked with 6 bailout bottles (small air cylinders for emergencies) and we evacuate to the gazebo located directly next to the habitat (the white tent-like structure on the live webcam). The gazebo has its own gas control panel to fill breathing gasses or mix decompression blends if necessary.
Aside from a few nuances of life underwater, it’s been surprisingly easy to adapt to living at depth. I still feel a bit of constant pressure on my chest and everyone sounds like they’ve inhaled a little helium because of the density of the air down here. Other strange changes that I’ve noticed have been losing my sense of smell (probably a blessing with 6, damp people squeezing in-and-out of pee soaked dive gear all the time smashed in a small, enclosed space) and things taste more bland (probably related to the smell). Still, the hardest thing to get used to is looking out the window while you work, eat, sleep or shower and seeing all the fish staring in at you.