Some elaboration on our dive preparation for this unfamiliar body of water.
Jabberjaw and npallasi did some snorkeling a few days earlier to check out the location.
We surveyed the shore area again a few days later, going up and down the north east shore line and discussed the pros and cons on various entry/exit area, and checked these areas physically to ensure that these points were easily reached, with surfaces that were not too challenging (no sticky mud etc). We also tried to ancipate the depth of water based on the terrain, but because the quarry was artificial, I think our guesses on the quarry profile was not entirely correct.
Crash prepared maps of the lake, and we used this for our mapping.
On dive day, we had 4 divers, split into 2 groups, with npallasi as the least experienced diver remaining on land supporting the divers. A dive plan was discussed, with discussions on depth, air and and time limits. Areas to survey was also discussed, with the first group diving to a more conservative plan.
We had the necessary dive and safety equipment, including shears/knifes, torches and backup, SMB, compass.
When the first group descended, the other 2 divers remained on the surface with binoculars and a map, we tracked the bubbles from shore and followed the divers as the swam along a pre-agreed path. The divers navigated with a wrist compass. The surface trackers used a GPS unit to track their shore location, and estimated the location of the divers - these locations were marked on the map every 5 minures.
After the first group ascended, they briefed the second group of divers who then, based on input from the earlier divers, planned their dive to explore another area. Again, we had a strict dive plan and direction to follow. Again, the second group were tracked on the surface via their bubbles.
We initially thought of dragging a SMB on the surface, but there was a concern that the SMB line could get entangled on fishing lines or submerged branches, so that plan was abandoned.
In the end, it was a good exercise, going through our training, and I think we all learned something new, even though we did not find anything too interesting in the dive site itself.
Anybody else with additional points to add?