About the site
I dived Olwolgin in 2010 and again in 2012 after the Downstream section had been discovered and while it was still being referred to as Unamed Cave. Even now, at a point where the Upstream areas of the cave have been dived extensively and finding additional passage is less likely, swimming through the twisty tunnels is an exercise in optimism. Dark water beckons from under scalloped limestone, just asking to be checked. The rock shapes here are beautiful.
About the dive
I’ve been out on the Nullarbor doing some filming up on the high plains, and it was nice to have a few days to play once the work was finished. Unlike my last trip out here, I had my rEvo in the car as well as my sidemounts. Tim and I were planning a bubble-free trip into Upstream Olwolgin. We knew we would be limited in which areas of the cave we could visit with a backmounted configuration, but with 2.6kms of passage there was enough to keep us occupied for a few hours of very nice diving.
After a wiggle through the entrance restriction we meandered down the main line to Babylon Lake to check out the hanging roots you can see at three and a half minutes. From the end of the main tunnel we headed back slowly, checking out the side tunnels to see which ones were rebreather friendly. I remember getting stuck in the Rabbit Hole in sidemounts in 2010 – with the rEvo on, I couldn’t get within 10m of the restriction. It’s been a long time since I dived with backmounts in an overhead environment and I had to remember to stay low through the low sections, rather than aim for the middle.
About the video
Olwolgin isn’t an easy cave to film, with bright white walls but dark water. The multi-layered halocline adds fuzzy effects through the water. On the other hand the rebreather made it much easier to film the reflection of the roots in the underside of Babylon Lake. We also had fun checking out the side tunnels. The footage is cut from my camera, filmed by both myself and by Tim, and from Tim’s GoPro. I had my Archon lights on camera, with a 3,300 lumen LED and a 50W HID off camera. If you stick it out to the credits, there’s a timelapse of the night sky as the Milky Way wheels over our camp – the best view in the world.