DPV Stage Cave | Blue Label Diving

Technical diver navigates a junction in Song Hong Cave
Tech diver navigates a junction at Song Hong

Three divers slosh through the Thai Jungle. Their rock boots sink in the dirt under the weight of their gear – a cylinder in either hand, a dive harness, and a host of technology designed to push the limits of human exploration.

Lighting the way with their torches, they come across a flooded pit – the unassuming entrance to the karst passage of the cave. Their dive computers are programmed with three breathing gasses to optimize decompression and they descend into darkness.

Krabi, Thailand is known for beaches and climbing. But the pinnacle-shaped mountains that dot the horizon also house the speleothems of the Sra Keow cave system.

Karst mountains line the horizon in Krabi. Underground, they house a technical diver's secret
Karst mountains in Krabi. Underground, the caves make training grounds for divers

As a technical diving intern with Blue Label Diving, I traveled to these caves for a DPV Stage Cave course. Ben Reymenants, owner of Blue Label Diving and technical instructor trainer would teach the ins and outs of Diver Propulsion Vehicles (DPVs) and Stage Cave diving. We began in the open sinkhole of Song Hong, a perfect location for DPVs.

We had set out days before from the Blue Label Diving office in Phuket, Thailand. Two trucks of dive gear were needed to secure an air compressor, two Megalodon rebreathers, three DPVs and enough cylinders for five divers to conduct three DPV Stage Cave dives apeice.

We sped under limestone traverses at Song Hong. The stage cylinders that had weighed us down in shallow water were clipped to cave line. You can’t describe how it feels – as close to flying as a person can get.

Now, in Krabi, we explore a different kind of cave. Sra Keow is too restricted for DPVs, but the skills we’ve practiced – staging cylinders – allows us to lengthen our dives with shortened decompression stops.

Ben Reymenants is first into the cave. He makes no bubbles on his Megalodon closed-circuit rebreather, causing no disturbance to the silted tunnels. Facing his students, he takes photos, which we later use to perfect our technique.

A cave diver makes a tie of using a reel. This will secure his continuous guideline to exit the cave
A cave diver makes a tie off. This secures a continuous guideline to the exit

On the way into the cave we approach a restricted passage. The cave line comes to an abrupt end and I, not wanting to block the passage, reach across to an adjacent line. This is almost a fatal mistake.

A cave diver must always create a continuous guideline to the exit. I fail to tie a ‘jump’ between the end of the line and the adjacent line. My teammate behind me, however, remembers. This becomes a problem when we turn to exit the cave.

My teammate followed his jump line when we turned. Not familiar with this line and unable to see my teammate in bad visibility, I continued along the permanent line.

When team members separate, the search for a lost buddy can quickly become the search for a lost body. I now found myself in this situation. Following my dive computer, I finished my decompression and got out of the water as quickly as I could. I grabbed emergency supplies from the truck – a mat, phone, isotonic fluids, and all the remaining oxygen cylinders I could find.

Ben, who had watched the situation unfold, retrieved my lost teammate. They finished decompressing and made a safe exit. I was shaken when they broke the surface, but had no choice but to take it as a lesson. I had breached cave protocol and, in doing so, endangered my entire team.

Later, we come to a mysterious hole. A 30 foot abseil into darkness marks the entrance to Sra Keow IV. Mud slides into the pit as Ben Reymenants, wearing a minimalist sidemount harness, lowers himself into the black hole. A team mate comes next, cylinders are lowered down, and they encounter little-known cave fish as they fin upstream into the mountain.  Surely, this connects to unexplored passages.

Ben Reymenants prepares to abseil into Sra Keow IV
Ben Reymenants abseils into Sra Keow IV

They  pause to take photos in a dry room – careful not to breathe the stagnant air. Mineral drips have formed stalactites that have been seen by a lucky few who can make the trip.

The team climbs out of the pit, muddy from the passage. For now, it is time to load the gear back into the trucks. They’ve conducted DPV stage cave dives, explored an underwater maze in the Thai jungle, and return to Phuket to celebrate a successful trip. They leave with pictures and memories of adventure that will last a lifetime.


Sidemount Divers Explore a Dry Room at Spider Cave. Their cylinders are staged for decompression as part of a DPV Stage Cave course.
Stage Cave divers explore a dry room at Spider Cave