Sometimes, not only do you need to be kept afloat in the water, but also you may be un-retrievable under normal conditions.
Here, and SOS Personal Floatation Device or Buoyancy Compensator combined with a Lifting Harness shows its value. Trying to launch or retrieve a heavily burdened diver, even in calm conditions, can injure the diver and damage expensive equipment, or worse. An integral lifting harness provides the solution. When combined with a PFD, retrieving and un-responsive victim from the water becomes easier and safer, for the rescuers as well.