Nothing can take the place of active supervision around the water.
C.E.O. just like that of a company this is very important. Constant Eyes On. We all know this is vital around the water. No floatation device or amount of skill can replace supervision. Yet most drownings happen when one or both parents are present.
However, let's be real. Constant Eyes On isn't something that is realistic but it is something to strive for. Something to not actively seek replacements for but to find ways to improve especially when around the water. Here are some ideas:
Phones and devices, just admit it we are all addicted. Have it close enough to use in emergency but far enough it doesn't distract you when your child is in the water (bathtub to pool).
Get in the water with the kids and be no more than an arms length away until they are old/skilled enough to be embarrassed by it.
Get towels and everything necessary for baths set up before putting your child in the tub. Bathtubs are the most common body of water for children 1 and under to drown in.
Be aware. Diffusion of responsibility is a psychological term that means we falsely assume that because more people are around more people are watching when in reality the opposite is true. More people means more distractions for everyone and in fact an accident is more likely.