After a check out dive in the Cabouy (which is big and dark with average vis), and the Ressel (which was lovely but a bit milky), I was excited about a trip into La Truffe. Rather than an active streamway, the water in La Truffe in summer comes from percolation through the limestone. This means the vis is crystal clear and very Gambier-esque. The tunnel here is smaller than the first two caves and stays shallow through a number of sumps over a long distance. Our plan was to dive the first sump and have a look in the second.
The one concern was the size of the entrance restriction. I was keen to take the rEvo in rather than moving to sidemounts. After a little wiggle through the entrance rocks there is a gravel slope flattener to get through. On first attempt I got myself in the right position with loop pressed into the gravel before deciding it wasn’t opening up fast enough for my liking. I surfaced and Georg spent 10 minutes with a small shovel rearranging the gravel. On second descent I was straight through and turned around in the clear water to catch the others emerging.
Ken was through next and after a photo or two caught my attention to point out the fog forming on the bottom of my dome port. I haven’t had a single case of fogging an 8” dome in my metal housing, so I thought it was strange. Luckily the fog only covered about 10% of the dome on the bottom left hand corner, so I recomposed the shots to allow cropping and kept going. I assumed the hot cars and hot sunshine outside, followed by the 13 degree water had caused the problem.
We had a very pleasureable trip through sump 1 followed by a walk/stagger across the rocks to the second sump. The second sump was even smaller and turning around to take pictures was difficult. I found a few good spots and I particularly like the half and half shot here which was taken just before we surfaced at the far end of sump 2. The floods in winter sweep the tunnel clean so there was very little silt to disturb.
The entrance restriction was no problem at all on the way out. Back in the sunshine I opened the camera housing to let the fog out and discovered a series of drops on the back right hand side of the camera body. That changed the story from a hot/cold fog incident to a minor leak – not good! I regreased the main O-ring and the following day had no issues. The fog returned with a vengence the day after however, and I took the camera back to the surface 2 minutes into the dive. Some further field maintenance to replace all the control O-rings on the right hand side did the trick, fixing the leak for the remainder of the trip (and hopefully the next few years). I was lucky to get just three or four drops of fresh water as a warning, especially half way through a trip.
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For my other images from the French caves, see my list of articles here.