lifebuoy
A ring-shaped flotation device designed to be thrown to a person in the water to provide buoyancy and to prevent drowning. It differs from an innertube because it is often made of solid floatable material (rather than being air-filled) and is oftentimes colored in a such a way it stands out of the water. It also has a provided line to pull the casualty holding onto it.
The following tags are aliased to this tag: lifesaver (learn more).