Currents and rip currents
Again the term “lake” does not represent the forces of nature represented in our fresh water seas. These, along with other strong currents can be present in apparently calm water. While rip currents are generally created by wave action, dangerous currents can be present even on glass calm days. Instrumentation on my boat has shown current speeds close to 2 mph which exceeds the speed most are able to swim. Check out this NOAA article on rip currents and what to do if you are overcome and keep in mind, this issue is has a lot more awareness in Michigan because the water temps are generally warmer on the west side of the lake. Swimmers, kayakers and other boaters in Wisconsin have been lost. Children are obviously most susceptible.
http://www.crh.noaa.gov/mqt/?n=whatconditionscauseripcurrentstodevelop?