“Flotsam and jetsam” is sometimes used broadly as “odds and ends,” but its origin dates back to the late sixteenth century as a description of debris left after a shipwreck.
Flotsam is whatever is left of the cargo or ship that is found floating on water.
Jetsam is cargo or parts of the ship thrown overboard to lighten the ship in an emergency and which subsequently sinks or is washed ashore.
Today the expression might also be used to describe debris from a plane wreck.
Flotsam came to English through the Old French verb fluter, meaning “to float.”
Jetsam is an alteration of the word jettison.
Valuable items thrown into the sea but attached to a buoy so they can be recovered after the ship goes down are called “lagan.”