At Expedition 3, the team of FCD’s Bernil and Doc and guest, Lou discovered the blockage of all accesses to Mayor’s Chamber by what is now determined as mounds of coarsely granular limestone. A cave-in deep in the area of Mayor’s Chamber was suspected.
Dive #2 of Expedition 5 was done solely to look for the site of the cave-in. Other than a small opening of barely 24 inches across, no possible source of the massive amounts of limestone was identified. (The small, mature looking opening on the ceiling deep in Mayors Chamber looked hardly a part of a dramatic convulsive geologic event).
This series of pictures (left to right) reveals a large cavitation right above Doc’s Door area.
(The still pictures above were ripped from FCD Bernil’s Hinatuan Video Part #2, from segment 1:00 to 1:13.)
I believe that the “redesign” of HERUC was a natural cave-in phenomenon right above Doc’s Door, totally independent of development around the area. FCD plans to do a follow-up exploration in the next few weeks to document this area.
PS: I always comfort myself and others when planning cave dives that frequencies of natural cave-ins are measured in eons not days, weeks, months nor years. If we fear being buried in cave-ins while diving Hinatuan’s Enchanted River Underwater Cave system, we would have to be diving for thousands of years…I guess.