Thinking back, this morning seemed like a week ago. The first dive of the day Mike L.A and I got into the flow. We headed out early to the northeast line and picked up with the coral science. In this study we lay down transect lines that are approximately 25 meters long, and then measure the 10 largest coral heads that are within 40 cm of the lines and the 10 largest coral heads within the area of the swath between the lines. For each coral head we also estimate the percentage of coral that is newly dead and long dead, and take photographs with labels that correlate to the data that we write down on underwater slates. This study assumes a random sampling and is designed to provide an estimate of coral condition for the deep reefs at the Aquarius site.

So that's the science objective. Operationally there is an art to laying out the lines quickly and safely. We need to use our cave reel lines to lay out the transects because the tapes are not strong and could break or float away, and then we might get lost. LA and I have figured out the best way to, or at least an efficient way to work together as a team to lay out the lines and then transition quickly to the business of measuring corals. We have done this before and do it today without a lot of talking. I like it better when we don't talk. It allows me to concentrate on the reef, its beauty, and the work. Also, talking uses a lot more air and energy in the full-face masks that we have. I would estimate that we use at least 30 percent more air when we are talking. It's great to have the ability to talk with our through water communication system, when we need it. However, sometimes talking gets in the way of communicating and when you talk a lot, usually you are not doing anything else productive. In any rate, today we used hand signals, talked sparingly, and got a lot of work done - we knew what we were doing.

We finished the coral study, then headed back to the habitat to pick up water sample tubes, and headed back out to an area called "shallow S4". There we go through a meticulous procedure to collect three water samples. The water samples and their chemistry are used in conjunction with an in-situ physical oceanographic instrument to assess localized up-welling phenomena (cold water from deeper water sometimes moves up onto the reef). After the water samples we support an educational outreach event and get a chance to answer questions from kids while swimming outside the habitat. The event worked out well and as usual the kids asked very good questions.

In the afternoon, we did a series of studies inside the habitat to characterize the sound and light levels at a variety of locations, and then filled out forms that relate to the habitability of the Aquarius. Then it's on to the night dive.

Three of the surface crew swam down and meet us in the wet porch of the habitat, and then the seven of us headed out toward the pinnacle. We moved out the line into the black Night Sea. Each of us had a glow stick attached to the top of the tanks. Our chemical lights mingled with the swirling natural chemical bioluminescence creating our own macro universe of swirling green lights. The sounds of bubbles, which rise toward the surface, reflected the moonlight as we pressed along the lines into the night. When we arrived at the pinnacle we checked in at the way station, then attached our cave reels and moved off the lines over a ledge into the depths. We started the excursion with our lights off and we could see the shapes of coral heads fading down the ledge and the shadows of fish moving through the dark blue water, with an occasional flash from their silver sides reflecting the moonlight or the chem lights. As we leveled off at around 90 feet, we turned on our lights and now our world moved from about sixty feet in front of us to five feet. It was a world of bright colors in the lights, sleeping fish under the ledges and free swimming night predators in the shadows. It was a calm, slow and quiet world; it is the ocean night.

The highlight of the day was the return trip home from the reef. We retracted our cave reels and hit the excursion lines and then began the long trek back to Aquarius. It seemed like forever. Then at about 200 feet out we saw the warm glow of Aquarius, no shapes just glow. As we moved closer the shape began to emerge out of the night, and then the details and the rays of yellow light filtering out of the port holes were visible, dancing off the sides of the barracuda and bait fish.

Then it's out of the gear and a hot navy shower.