Lobster buoys are colorful floats that are attached to lobster traps. Traps are submerged, so the buoys mark their location above water and allow lobster fishers to retrieve them easily.
The buoy also serves as a warning that there are underwater lines present that can snag on a passing boat. Many fishers set traps in groups, with a single buoy marking their location. The multiple trap lines can be hazardous.
Lobster buoys are used to distinguish one fisher's traps from another. The state of Maine, for example, requires that lobster fishers mark their buoys and their boats with the same color pattern and prohibits the same color patterns from being used by two different fishers in the same area.