Clothes appropriate for the season. Remember, this is Wisconsin, weather can change throughout the day.  Lake Michigan can make it cold even when it is 90 degrees just a few miles inland.

A snack and something to drink. 

A valid Wisconsin Fishing License with (if appropriate) trout stamp(s).  You need to carry a paper copy when fishing Lake Michigan and other border waters.

A cooler if you plan on keeping any fish. I do encourage catch and release for many species of fish.

A camera for the trophies and mother natures beauty.