Selling goods when they are still on the ship or plane; who is liable for them if they are damaged or destroyed?

Someone bought a shipload of rice, and before the cargo reached him and was received, he sold it to someone else. Then soon after that the ship sank. Is the transaction valid, and who is liable for the loss of the cargo? What about goods that are brought in from abroad, whether by plane or by ship – once the goods are no longer in the possession of the seller, after shipping, and there is documentation of the transaction between the two parties: isn’t that regarded as receipt of the goods? Or is it stipulated that goods should be received and taken away by the purchaser? Who is liable for the goods if they are damaged or destroyed in this case? What about selling goods that are already on board ships at sea, where they are at risk of accidents and destruction?