As we swam away from the Aquarius Undersea Laboratory, from a distance, our new home on the sea floor looked like a massive mid-evil iron ship standing tall against the blue water and the gleaming white sand. It's once bright yellow paint transformed by green algae and encrusted with mustard fire coral and small red tube sponges. Underneath the habitat, schools of yellow tailed snapper, turquoise blue parrotfish and a huge grouper the size of a Harley Davison motorcycle.

We swim along the front porch of the habitat and intercepted the excursion lines that head off into the blue and the far corners of Conch Reef, over three miles offshore of Key Largo. We are wearing a technical diving rig. Twin 100 cubic foot tanks, twin regulators, and tank isolation manifold in case any part of the system leaks. We also have full-face masks and a through water communication system that constantly crackles in your ear as you move through the current out to the worksite on the reef. The visibility (based on water clarity) is capable of radical changes over short time periods at Conch Reef. Anytime we want to move more than a few feet off the main navigation lines, we have to attach a cave reel that allows us to spool out line so we always know our way back to the main lines, and ultimately back to the habitat. Surfacing is not an option; neither is coming back to the habitat low on air, or later than planned. Saturation diving is a superb way to conduct science, but a serious business of minutes and feet and executing as planned.

Today we are doing a survey of the extended reef and checking in at each of the two remote way stations to practice refilling our tanks, a technique we will use tomorrow when we start the coral reef studies.