Sallyann1234,
It was you who first suggested the dye marker idea, no?
As mm43 mentions, wouldn't most of it diffuse and become virtually undetectable when mostly released from wreckage 4000m down?
I just don't know enough about the properties of dye marker, is there any information about it anywhere on the net?
Oil seeping from a shipwreck can continue rising to the surface above the wreck site in globs for ages, remain visible on the surface, and pollute beaches for ages, too...
So there may be merit in the idea !
CJ