While giraffes have the ability to float in water, there have been no definite observations of giraffes actually swimming, according to Scientific American. Ethical concerns make it difficult to test a giraffe's ability to swim in deep water.
Giraffes may be able to swim, according to mathematical formulas; however, no one has actually seen them do so, according to The Telegragph. Even if giraffes can swim, they are probably poor swimmers because of the way they navigate land. They move their necks in an up and down fashion in concert with their legs, a movement that is not compatible with propelling a body in water.