When are swimming lessons best?

I like to start 4 yo: A child must be taught a variety of things about water that can be phazed in over time. A playfulness & joy around water can be taught in infancy, with close hands on control. This can prevent outright fear that grips some older kids & hampers teaching swimming & safety later. I like to start formal lessons at 4 when their communication skills are good & can be taught a respect for pool dangers.

Swimming: As this isn't a real medical question i will jump in ( ha ). I started my kids when they were quite young - about 4 with gentle introductory fun. I taught swimming in high school and swam in hs and college as did my son. Be sure to not create a fear of the water and your kids will have something to enjoy their entire lives.