There was a special ship charted to collect the body's from the wreak site of were the Titanc sank. I can't remember the name of the ship i think it was the marconi barnette.

I knwo there was few bodys which were barried at sea and in the ship bodys were placed in refrigerators and then taking to newfoundland.

The bodys that sank to the botom was because the air that was left in there body's and once this happan's the same principale of the sinking except they sink to the bottom of the ocean and then the humence presure at the depth's crush the bodys and because there isn's certain preservatives the body decay and either get covered other by tones of silt wich then gets compact and other years to come proberly end up oil again.

I be greatfull if i am wrong someone correct me