In the dead of winter I was up up north staying at a family cottage and on the second day I was there it was extremely warm. Well, extremely warm for northern Ontario in January, the temperature popped up above zero and the sun was out in full force. The river was frozen solid but the full day of warmth melted a layer off the ice leaving about an inch of water on top. Then when night fell the temperature changed quickly and severely as a cold front entered the area, plummeting everything back far below zero in what seemed like just a few minutes. In these situations the ice makes crazy sounds as it freezes and shifts. I was hoping to get out on the lake and get some stereo recording of these sounds but the wind was just too unforgiving and even with my blimp the wind noise was too loud to get any usable recordings of the ice. But luckily I had brought my Hydrophone, underwater microphone.
After everyone else had gone to bed, I headed out on to the frozen river looking for a crack I could drop the hydrophone into, hoping that maybe I could get some of the huge ice shifting sounds from underneath and avoid the wind altogether. The ice was very thick, more then 6 inches, so it took lots of roaming around in the pitch black night, before I found a good crack with a small hole just barely big enough to get the hydrophone through and immediately found I could hear some crazy sounds.
This is a picture of the crack in the ice with the hole and the hydrophone's cable coming up out of the ice.
I also took some time to grab some blocks of ice near the shore and smash them on the ice surface above the where I was recording. It was so cold and I had been out on the river for such a long time by this point that I was having trouble fidgeting with record levels on the gear because my fingers were starting numb up a bit. This did not really work out as I had hoped as the sounds are not that interesting, but something that is kind of cool is simply the sounds of my footsteps walking around above the mic. They could be useful someday. Here is a clip of a bunch of impacts followed by footsteps at the end.