Casket-salvaging scrimshaw

The casket-salvaging scrimshaw is an item that can be made with the Fletching skill at level 90 once all four scroll fragments of casket-salvaging have been retrieved from the Player-owned port, using 10 ancient bones.

When equipped, it offers a chance at finding a casket containing a random reward, including gems, divine locations and port resources.

This is the Fishing equivalent of the gem-finding and tree-shaking scrimshaws.