After waking up in Phil's nice warm trailer, we get up extra early to make it over to the general store in Custer to get setup for a objective trip into Big Bat Cave.  The entrance was through a culvert that was vertically installed into the ground for a nice entrance into the break down pile.  Once we all got in, we went over a series of breakdown passages stoop walking and crawling passage till we got to a Tyrolean traverse.  This was a 18ft pit that had a hand line in place to hold onto so nobody fell into the pit below.   After we passed this point we came up to another series of breakdown piles and into this room that had some fascinating fossil biota.  It was quite a large fossil but we kept moving on until we came to a junction the slot canyon passage, than down through the Kentucky Crawlway and out into the river passage. This was quite interesting as the water has cut some sections of the river cave with general fluted walls and scalloped rock. At other parts the passage was standard Midwest river passage. We went up into a side passage at was a bit more dry and came back down pass a chert cannonball room and back out into the main trunk which would lead us to the sump.

Sump in Big Bat Cave Kentucky

We continued down passage until we got to a section where John wanted to follow a side lead to see if it will continue and the rest of us continued down the river passage and at times the water got so deep we had to start swimming. Eventually we got to a breakdown Rotunda Room and the sump was in site. Beforehand, John was explaining to me that over 13 different leads exist which will extend the survey into virgin passage but might develop options for cavers to pursue different directions in the cave.

Sump in Big Bat Cave Kentucky

I agree that a continued push Into the side passages may uncover more levels, more passage, and might also help cavers to enter the cave from the surface down into different POI's including a more direct route to the sump.

Sump in Big Bat Cave Kentucky

The traverse to the sump was a fun one and it can be done with regard to dive gear but it will require gear to be packaged with padding and handled carefully which can be a challenge in the belly crawl and breakdown passages, BUT no doubt, it is a workable process especially with a group of around 16 cavers like you mentioned.

Sump in Big Bat Cave Kentucky

A connection to the lower river passage through one of the potential leads will be very helpful for a dive to take place and add another margin of safety.

Sump in Big Bat Cave Kentucky

The beach-sand hill can not only be used as a staging ground, but the passage at the top can be used as a warming station which are two important advantages to this dive site. They overlook the sump which is really nice.

 The room is a small rutunda room that I have seen in sump passages before which is interesting.

The water level the cave was reported to be near normal.

The sump itself was a static pond with an estimated measurement of 20 x 30 x 10 ft in height decreasing to 0 feet within the length of the pond. There was foam bubbles covering the surface water and the water visibility was around 3-5ft.   The depth was unknown for most of the pond except for a few estimates that I will mention shortly.

There was a flowing river that went into the sump that eddies right down river. I felt around the eddie pool and found no going submersed passage. I also found a small dugout " sea cavern" like feature that looked like a continuation of the River eddie pool water action with no going passage. This appears to be a overflow dugout where higher water levels act and slot erode this feature.

Left down river, I did not find any features with a foot push or a mud silt flow check. There was surface organic matter floating in this corner.

Sump in Big Bat Cave Kentucky

Back center is where I suspect that the submerged passage will be found. There was a structurally solid   limestone ledge with a sharp lip and a drop off in this section.  Walter and I took turns dipping into the water and I was able to hit the bottom which is estimated to be at a depth of 10ft. I stuck my feet under the ledge for a bit while we traversed the ledge and it appeared to go beyond my reach. The actual passage may even trend a little left from sump back center but I can not confirm that. After dipping into the water it appeared to stir up the bottom decreasing the viz so it appears that the bottom is silty.

My conclusion is that this submerged passage might be quite small due to the static pool of water and foam bubbles on the surface. Although there was no organic material or garbage floating in the pond, indeed the water is losing into a unknown passage.  There was no indication of a whirl pool other than the eddie pools to the left and right.

Sump in Big Bat Cave Kentucky

With the actual submerged passage being quite uncertain and the high probability for a small siphon insurgence with zero visibility conditions will likely be found, the risk of the dive must be considered.

In my opinion, I feel that a recon visit to Chris's cave is a necessary trip to not only only mark the sump that will confirm a dive connection if one is attempted on either side, but will also give us the option to choose a more feasible dive plan which will include the traverse with the dive gear in the dry/semi dry passages leading to the sump. Furthermore, Chris's cave must be the receiving end of big bat and will be a resurgence which can add a margin of safety to the divers.

I also have had a thought that the water in the pond of big bat cave may just percolate through the bottom and contact with impermeable rock where it starts traveling to Chris's cave without a passage big enough for human travel.  I want to thank John Sies for laking us through the cave and giving us some great insight into Big Bat Cave.  John is very experienced with this cave and with his help we were able to develop a plan to look into this dive a bit further.  The next bit will be to visit Chris's cave to see what the connection sump looks like from that end....to be continued.