By way of explanation.

jetsam, flotsam, and ligan

The Columbia Encyclopedia, Sixth Edition | 2008 |

jetsam flotsam, and ligan [O.Fr.], in maritime law, goods lost at sea as distinguished from goods washed ashore (wreck). Goods that remain floating on the surface after a shipwreck or accident are called flotsam (or floatsam or flotsan), while jetsam refers to goods thrown overboard, or jettisoned, by a vessel in distress. Ligan (or lagan) designates goods that are sunk in the sea and have a buoy or floating object attached to them as a mark of ownership or in order that they may be found again. Such goods found by other persons must be returned to the owner, while flotsam and jetsam must be returned only if the owner makes a proper claim. The rules of salvage apply to all three types of goods.