Looting or Salvage?

Readers may be able to solve a debate a few of us were having yesterday.

If containers from the Rena wash up on a beach and there is no representative of the owner there to claim them, is it looting to help yourself to the contents, or it is salvage under international marine law?

I think it qualifies as looting as people surely know who the owner is, but a lawyer friend (not a specialist in marine law though) said that people have a right to salvage anything that washes up unless the owner is there to claim it.

Anyone want to clarify the law?