Did an exploration on a promising marsh a few days ago. The area was a marshy valley basin thats mountain spring fed, and clay based. I hiked the perimeter of the basin, and was then able to skirt one of the large flat stretches in the middle. I was crossing via an old log mostly, but I stepped off and the ground held though was mushy in its feel and consistency. I made another step and heard bubbles coming from somewhere nearby. I kept within an easy reach of that old log just in case the ground were to give under me. Another step more bubbles and the result was the feeling of the ground getting more squishy beneath my feet. I got back onto the log and back to the 'shore' area and found myself a nice long deadfall stick/pole and returned to where I had been walking. I walked back out onto the flat again, and placed that stick between my feet and pushed, It went in easily and I kept pushing, down and down, and down deeper I pushed that stick. I finally found someplace that felt like the stick got stuck at/stopped going down, and I pulled, and pulled, and pulled some more, (meanwhile hearing bubbles elsewhere close and my shoes oh so slowly sinking down even as I stepped apart to balance myself out some. Well in the end, I held the stick up to my body and saw to my surprise that the mud right where I was standing at was actually up to at least my chest or probably deeper, I had run out of stick more or less!!! I just gotta go back there when the weather warms up and perform a more in depth test I managed to free my shoes with sucking gross noises, and got back to 'shore' without further incident, but I hadn't even gotten out to the middle and it was that deep, I really am curious how far it goes... I have some pictures of the area coming here soonish too.