When we started working, it was indeed that narrow. I was wearing doubles, and I could barely fit through it. I had to go straight down, scraping the sides as I went, and then arch my back when I got to the change in slope. One of our team's jobs was expanding that opening.
We had three teams working. Shane and Mike were the only ones who went past the restriction at about 140 feet (one of the mistakes in the video) to do the deep exploration. We had two others (whom I will not name without their permission) working on that restriction, and the rest of us worked to open the passage from the opening at 85 feet to the 140 foot restriction.
Even after we moved a lot of rocks from the upper area, it was still a tight fit. The afternoon before the fatal dive, Mike talked about how they were always dislodging rocks on their initial ascent, so I went in alone on the last dive of the day to try to remedy it. I had to be alone because I intended to make a serious mess of things. I had a specific time plan so that if I did not come out on schedule, someone would go in after me. I started by carefully moving loose rocks at about the 100 foot mark, and when I got close to my scheduled time, I began to work my way upward, shoving my arms into the loose clay and rocks all the way to the elbows, pulling out as much as I could, and throwing it behind me. I kept my eyes up at the halo of light in the siltout. I knew I was out of the cave and into the Blue Hole when my arms no longer went into that mess--that's how silty it was.
So the opening was greatly expanded over what it was, and my description should tell you that it is loose and unstable. I am sure a lot of it has collapsed since then.
We mucked things up pretty seriously every day. The flow from the cave was enough to clear it out in about 30 minutes.