The
two major classes
of buoys used in the
Coast Guard are
Ocean Buoys and River
Buoys. Ocean buoys
consist of unlighted
cans, nuns, and
spheres, as well as sound
buoys and standard
lighted buoys. Standard
lighted buoys are
designated by IALA as
pillar buoys. River
buoys consist of unlighted
cans and nuns with
specially designed fins
and counterweights.