Salvaged Strongboxes appear below the water under floating burning debris.
Description
Well, I was able to make enough repairs to this gear to let you dive for awhile, anyway. I wouldn't count on it holding out for a long time, though.
The wreckage of this ship is strewn along the bottom from the east cost of this island out toward Alcaz Island. While this helm holds out, locate pieces of the wreckage on the bottom between this island and Alcaz. Use this salvage kit to search the wreckage for pieces of the cargo. Be careful not to venture too close to Alcaz Island. Those hydra are fierce.
Progress
Did your search of the wreckage reveal anything about the Defias cargo?
Completion
<Renn rifles through the contents of the strongboxes you recovered.>
Good work. Now, let's see if our 'precious cargo is in here...
Cut Scene on completion
Renn McGill says: Hmm... old coins... ugly jewelry...
Renn McGill says: More ugly jewelry... letters home... I'm beginning to give up hope!
Renn McGill says: Hey... what's this? A pair of manacles and not just any. These are enchanted. This cargo, it wasn't a thing... it was a person!
Look for floating wreckage (much like fishing schools) on the surface of the water, then swim down to the boxes on the bottom of the sea and use the Salvage Kit to collect them. Also, wreckage with fewer fish contains a box and not a murloc.