snrub, your description of dropped fishing rods being above the thermocline reminded me of a dive I made in Jackson Lake, in Grand Teton National Park, to attempt the retrieval of a friend's rod. He had marked the spot with GPS. I double suited up, guessing the water would be cold. The lake may reach 68 or 70 degrees at the surface in mid-summer.
Overboard I went. My friend had the bottom depth measured at 34 feet. At 22 feet I hit the thermocline. The cold intensified. Darkness set in. When I touched the bottom, I could not see my hand in front of my face. I could not see my bubbles. I didn't have any way of knowing which way was up! Needless to say, I wasn't seeing anyone's fishing rod.
I added air to my BC and rose up through the water column that way. Just below the thermocline, my sight returned.
That was really spooky down there in the cold and pitch blackness!
