What's the difference between a Type III foam vest and a Type V inflatable PFD?

Type III foam vests provide constant flotation the moment you hit the water and need no maintenance, which is why reviewers favor them for non-swimmers and rough conditions. Type V inflatables (manual or automatic) are far less bulky and cooler to wear, but they require periodic CO2 cartridge checks and are generally rated only for users 16 and older who can tolerate a brief delay before inflation. Foam is the safer default; inflatables trade some safety margin for comfort.