Other forms: flotations
When something is buoyant, carried on the surface of water, that's flotation. If you have a swimming pool in your backyard, you definitely need at least one unicorn-shaped flotation device.
The ability to float is flotation, which can also be spelled floatation. A flotation device can be a safety feature on a boat, like the floating foam rings that can be used in case of emergency or the life jackets sailors wear. It can also be for fun, like an inflatable raft you use for floating around a pond. The Old English root of flotation is flotian, "to rest on the surface of water."