Stand up quickly in these ice caves and you risk impaling your head on an icicle....
When it's -20 and the pressure is high, you can explore with no fear of falling through to the water below! These amazing structures are formed by wave action offshore when frozen chunks break off and are heaved into the shore at crazy angles. They form bridges, caves, mini moulins, and spectacular beauty.
If you look closely, you can see bands of really hard, blue ice in the walls of the cave. My light metre went crazy when I was inside, and when I was very quiet, focussing for a shot, I could hear the ice crack and moan. This got my attention....almost stood up!
Georgian Bay is entirely frozen, and NASA has the pics to prove it. Good luck to the ice-breakers, due at the end of April!