Deep Exploration of Thom Song Hong Cave

Posted on 04/26/09 No Comments


song-hong-caveUnbeknownst to many tech divers around the world, Thailand is speckled with caves and caverns from north to south, many of which have never been fully explored. Earlier this month Aquanauts’ Roger M. Smith and fellow ANDI Instructor Bruce Konefe tackled the vast Song Hong cave, accessed via a sinkhole in remote Trang province.

Dived by only a handful of people since its discovery in 2006, the cave, about 960 km southwest from Pattaya, was notorious for its hard-to-find location, but has now been plotted on Google maps. It’s believed to have two entrances, but the easier-to-access opening is about 12 meters down in the 110-meter deep sinkhole. It then opens up into a huge cave, so large a light beam will not reach the opposite cave wall.

After the 12-hour journey from Pattaya, Smith and Konefe (along with support diver William Hudson of Mermaid’s Dive Center in Pattaya) unloaded, assembled and checked their bail-out tanks and regulators, making sure all were marked correctly.


Next was some alone time with their rebreathers. Konefe was diving his APD Inspiration Classic and Smith would be on Aquanauts’ ISC Megalodon. Quiet prep time is essential with rebreathers, as distractions could lead to dangerous mistakes.

The two divers and Hudson then went over the dive plan.  As the day drew to an end it was time to eat and get an early night.

Dive Day

Dive day started early and the team went through final details over breakfast. Then it was time to make our way to the dive site.

“While Song Hong is in a wooded area, it’s still easy to access. The three went down to the water’s edge to fine tune logistics. Bail-out tanks were given a final check then placed in the shallows. Next it was time to gear up. Final checks and adjustments were made with Hudson’s help.

“Carrying the 12 bail-out tanks, the trio made their way to the entrance of the cave and the task of staging tanks began, with the objective being to stage down to 100 meters. Smith picks up the story here:

“We started the long decent. Visibility was around 10 -15 meters for the first 40 meters or so then increasing to about 20 meters as we descended further. The cave was huge; we followed the left wall, occasionally seeing the ceiling or bottom but never the right side wall. Periodically we encountered huge rock formations akin to something you might see on another planet.”

While many envision caves having rows of stalactites and stalagmites, that isn’t the case with Song Hong. “Every cave is different, that’s what makes them so exciting,” Smith said.

“The staging of the tanks went smoothly,” he continued. “We hit our target depth of 100 meters ahead of schedule and turned the dive. William met us at the 21m stop. And all was OK.”

The Next Day

mapDay Two started in much the same way, with breakfast then off to the cave. This day’s objective was 130 meters with a 30-minute bottom time with a total runtime of six hours to allow for a long, slow descent. If successful, the pair would match the longest and deepest dive in Song Hong and they’d be doing it without the DPVs a previous team used.

“Having made a few adjustments to my setup, I was looking forward to a comfortable dive,” Roger said. “Seeing the staged tanks during our decent made gave us a comfortable feeling. We moved at a good pace and again were ahead of the planned time schedule. Passing our last staged tanks, we soon reached 120 meters and were feeling good.”

But at 124 meters, the unexpected happened. Bruce, in a post on the Rebreather World message board, described what happened next.

“We had gotten near are depth limit (actually 124 meters) when a pressure gauge imploded on my rebreather,” he wrote, saying that when it initially happened he heard only a loud bang. “I was not sure of where the bang came from, but first thing I did was check my gauges. The glass of the diluents gauge was all cracked with parts of the glass missing. I did not see any bubbles or any loss gas but figured it was time to go up.

“I stayed on the loop but checked the gauge readings more often. At the surface when I looked at the gauge the needle was stuck in place. I have not checked the cylinder pressure to see if there was any lost gas, but I do not think so since there were no bubbles; just a loud bang.”

Roger also said the ascent was non-eventful and the pair recovered all the staged tanks, handing them off to Hudson at one stop.

The unfortunate equipment failure cut short a spectacular and challenging expedition. The planned run time was six hours, but the divers managed less than two.

“We will return later to push further,” Smith said, “but, for now, we were both satisfied and well and felt grateful for the excellent support from William.”

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