Just a quick post to say that the underwater Disto didn’t work quite as intended, I made a number of trips to Sump 9 in Porth Yr Ogof this summer with the aim of surveying it accurately. The water is usually crystal clear on entry to this sump however the laser was not able to read the short distances I had hoped it would. For shots that should have been 1 to 2 m in length it was just returning valves of around 0.15 m every time, the bearings will be useful but I need to return and measure the lengths traditionally.