Most driftwood is the remains of trees, in whole or part, that have been washed into the ocean, due to flooding, high winds, or other natural occurrences, or as the result of logging. There is also a subset of driftwood known as drift lumber. Drift lumber includes the remains of man-made wooden objects, such as buildings and their contents washed into the sea during storms, wooden objects discarded into the water from shore, dropped dunnage or lost
cargo from ships (jetsam), and the remains of shipwrecked wooden ships and boats (flotsam). Erosion and wave action may make it difficult or impossible to determine the origin of a particular piece of driftwood.