What about bones?
A strange thing about “Gitche Gumee”, Lake Superior. It is normally a very COLD lake, freezing over in the winter, and it is also rather deep. Under those conditions, the bottom layer of the lake is rarely warmer than about 36 degrees, and organic decomposition does not occur. Whatever methane forms, does NOT rise in the upper levels of the water, but forms something called “methane ice”, a strange compound that can remain stable at temperatures below about 40 degrees Fahrenheit, keeping the methane from bubbling to the surface as a free gas. This substance prevents any further decomposition from taking place, and “fossil lumber” recovered from sunken vessels has been found in a near perfect state of preservation, so much so that is highly prized for fine furniture making. Presumedly, any bodies would still be relatively intact, even to the clothing, as a kind of mummy.
6⁰0 + feet down with no oxygen. Probably bones down there. But they will probably fall apart when you touch them.