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This cave was first explored by the 2007 expedition. The entrance is located on road 20, just above the main river sink for Phong Nha Cave. The team explored 200m to an exit below the road, leaving a couple of leads. With a day to spare, Watto Sweeney and Deb decided to complete the exploration. There was a reasonable potential for a way into the upstream section of Phong Nha cave.
We rigged the pitch and changed into wetsuits, knowing that out first lead was a deep wade or swim. Descending the pitch we soon reached the canal we had left two years ago. The water levels were clearly lower, but it was still a deep wade. After about 60m, the passage enlarged. The wet way continued, but there was a dry passage up on the right. Continuing through the water we emerged onto sand banks. Around a right hand bend we unfortunately hit a squalid mud lined sump pool. There was an underwater passage clearly visible.
Returning to the dry side passage we surveyed down to a junction. The inlet on the right led back through a small gour floored passage to the main entrance passage. Continuing downstream, we climbed through some blocks to enter another canal, this time all swimming. The large passage continued as a high level above. After about 150m of swimming with an amazing echo, we were convinced we were about to emerge into Phong Nha, sadly another sump! The water here is very deep and clear, with a slight flow down to the sump.
Another apparent lead from last time couldn’t be found. A ledge 3m down from the top of the pitch led via 15m of stooping passage and a 4m climb, back to the main passage. In the other direction, an exposed traverse and climb led to crawling for 50m towards the entrance. The passage ended in a loose boulder choke with surface debris on the floor.
Hang 11 was extended by about 400m to a total length of 618m
The sumps would be an easy diving prospect, with a definite possibility of a connection with Phong Nha.
This will be an objective for the 2010 expedition.