I recall reading an account of the Finns using home made dynamite mines and anchoring them in a lake. When it was frozen enough to drive on the Soviet Army launched an attack across it and the Finns command detonated the mines and sank a large bunch of Russkis into the freezing water.
If this happened it would seem there must be a large amount of goodies and vehicles waiting to be found on the lake bottom amongst a whole lotta bones.
A lot of what were lakes 75 years ago are bogs and peat marshes now. And there are all sorts of interesting things that turn up in them from time to time. A lot of the Soviet tanks used during the Winter War were gasoline-engine T-26s and amphibians; during the Continuation War the 76mm gun T-34 became more common. And yep, some of those recovered T-34s were put into Finnish military service.