I suspect that those who explore underseas wrecks are careful not to publicly disclose what they observe with regard to human remains; there is a high potential if such observations are disclosed for an emotional and negative response from the public.

I seem to recall that human remains were recovered in the excavation of the Vasa in Stockholm Harbor. The survival of such remains depends on a whole range of factors including water temperature, rate of sedimentation, and presence of marine organisms that dine on such fare.

Charley Noble