Trieste II Dive Number 10-77 was a Thresher site survey made in August of 1977. Site depth here was 2530 meters. My dive was number two of three at this site. One of the objectives of this dive series was to locate the reactor compartment which had never been sighted during the previous site surveys. The first dive (Command Pilot was OinC Kirk Newell) did not locate the reactor but got one of the truly outstanding photos of Thresher ever seen. The sail had been ripped away at the junction of its base and the pressure hull. It was tipped on its side with the underside sail plane embedded in the sea floor. The angle of the photo was looking up into the sail from the bottom. Fully exposed were the stumps of the masts, still bright and shiny and the sail numbers plainly visible with only a very light dusting of sediment. A great photo of a sad sight. Dive number two (my dive) was no more successful in finding the reactor compartment. I did locate the 'disturbed' area, a wrinkled mound, photographed by USNS Mizar and identified as the probable site of the reactor. I was able to fly over this area and to drive around its periphery. Aside from seeing several 'pools' of shot dropped by Trieste I several years earlier, I saw nothing suggesting an impact of anything as massive as the reactor compartment. I also drove up to the forward section to try to make a better photographic survey of this area of the site. Straight ahead visibility through the forward view port was never good due to the downward inclination of the viewing axis. This meant that during the approach to the wreckage area that I could not see more than about 20 feet ahead with relatively poor peripheral vision, as well. I used the port and starboard pan and tilt units to get the best video coverage possible but that just meant that I would not run into anything big. Once at the forward section, I stopped and waited for the sediment cloud to dissipate. During this wait, I used the camera on the aft pan and tilt to see what I had passed on the trip in. I was astonished to see a series of about seven or eight banana-shaped objects standing on end like a group of stunted trees. These were HP air flasks that had been wrenched out of their foundations within the ballast tanks and strewn around the wreck site. Had I been able to see what these were during the approach, I would not have come in from that direction. When the sediment cleared ahead, I could see the remains of the forward section. I had seen photos of the section (again, the Mizar photos) taken from an angle above the wreckage. Seen from my horizontal viewing angle, I was able to get an impression of the size of this section. Looking at it, I knew it had been the entire forward section of the boat but I could see only ripped and torn metal - nothing that was recognizable as part of a submarine. We spent about two hours at this site and the three of us had adequate time to study the wreckage via the view port and the three video cameras. We all reached the same conclusion, in that we recognized nothing that could be associated with a submarine. I also felt a sense of melancholy knowing that this heap of unrecognizable twisted metal was the resting place of part of a crew of over a hundred submarine sailors. When it was time to move on, and since backing out was not feasible, I dropped shot to get some vertical velocity and then used propulsion to move up and over this site without touching it and without dropping any shot onto it. The photos gathered here did not provide any additional insight into the cause of this tragedy but, simply by seeing these things, I came away with a vivid impression of just how fragile man-made things could be in circumstances like this. My log records this dive as 20.3 hours in length. Considering that I had conducted the Pilot's Pre-Dive checks, I had spent well over 24 hours in the sphere. It was every Trieste pilot's intention to stay down as long as seemed reasonable to allow the crew topside to get some rest. Remember, with Trieste, the time from launch to dive was sometimes two days of uninterrupted work. If I had to spend more than half an hour today in that cramped sphere, my knees would never work again.