Uncertain Principles: Heavy Heavy Water

So is it plausible that barrels of heavy water might’ve sunk, while barrels that contained ordinary water floated?

One thing not considered, or another way of looking at the problem: given the conditions of February in Norway, what if the heavy water had already frozen inside the full barrel. Would heavy ice float? It has a density of 1.0177 g/cm^3 (vs 0.917 for regular frozen water) and freezes/melts at 3.82 °C. Water has a maximum density of 1.0 g/cm^3. Even not inside of a metal barrel it would definitely sink, if it were 100% D2O. If the barrel were 10 kg, then we could suffer 50g/L of “missing” deuterium, which is roughly 50% “heavy.” More if the barrel were slightly more massive. 200 L of regular ice would give displace up to an extra (1000-917)*0.2 = 16.6 kg of water, meaning it could support 36.5 lbs of metal at neutral buoyancy. I thing we’re still in “plausible but not proven” territory.