Jackson Blue Main Line Penetration (1200')

Tuesday we woke up at 6h30 and headed straight for the hotel breakfast buffet. This has quickly become our ritual. With the Invisalign orthodontic braces that I'm wearing, it's a mission for me to get my teeth clean after eating at the dive sites, so I stock up on as much breakfast as possible and then just gobble yoghurt for lunch. Then we assembled the machines and headed to Cave Adventurers. Edd was very busy getting ready for the last day of a cave course he was teaching, but we got the Minnus payment sorted out and collected our O2 and dil fills, and then headed back to Jackson Blue.

The plan for the day was to do one long cave dive in the morning, and then go back into the cavern and mess around with our scooters so we could get a little bit of practise before the course started on Wednesday. The first dive was spectacular. We took the same route along the main line. This time I was leading the dive. The flow was much heavier than yesterday, but because we're on rebreathers we can just take our time with it. Kev had two stages and I had one, so we were definitely safe for bailout gas all the way to 2000'. Between 900' and 1000' there is a T where the line splits left and right. We followed the right passage and went all the way around until 1200' (365m) where there is another T. We knew from the maps that this was the joining of the line that had split at the first T. At this point it was 47min into the dive, so we turned it and headed back.

Map of Jackson Blue along the left main line to the second T

We had decided to do an out of air practice drill on the way back and I had wanted to do this at the first jump so that afterwards, if there was time I could reel the jump and we could explore a bit more but closer to the entrance. Unfortunately, Kev thought that we were going to do the skills at the entrance, so at the first jump when I flashed him that I was out of air and needed his bailout, he thought I was really in trouble and that my own rebreather and bailout had both failed. He dashed over to my aid and we both silted quite a bit swapping cylinders. I swam along the line to get out of the silt, then hopped back onto my machine, and turned to Kev to decide what we should do next, but since he thought I'd had failures, he called the dive and got quite agitated with me taking my time to leave. I only found out after the dive why he was so concerned. That's how it is with scuba, if you don't have the same plan then things get messy.

We were both quite tired after the dive, and I was freezing. My dry suit is leaking badly through all the seals, so I'm actually worse off than diving a wetsuit. But on the Catfish Hotel dive, when I used the wetsuit, I'd realised how unfamiliar I am with diving the machine in a wetsuit, so in order to be comfortable on the DPV course, I wanted to use the dry suit. The water temperature is 20C, so it's not too cold, but an 80min dive gets you shivering. After warming up a little we decided to do a short dive with the scooters and then pack up.

First we both scooted around in the tiny hole at about 1-2m depth just to feel how they work, then we descended into the cavern where there's enough space to scooter around that big dome and not crash into anything. I found the Minnus quite difficult to steer at first, and on a low thrust setting we realized just how bad our trim is - we were going really slowly. But it was fun and towards the end of the dive we were at least both zooming along and ducking left and right around the cavern without stopping and starting too much. Hopefully ready for the course, we packed up.