ice fishing in Maine you may want to get familiar with how much ice thickness is safe. There are a couple of sources of information for this info. One is an "Estimated Lake and Pond Ice Strength Chart" offered by Maine Nature News. Another is a "Blue-ice strength chart" provided by bangorinfo.com. The US Army Corps of Engineers has their chart and an explanation of ice thickness at "Ice Thickness and Strength for Various Loading Conditions". The wikiHow website provides an article on "How to Know When Ice is Safe".
At the far end of the ice fishing season you have the "ice out" dates. So what is an "ice out" date? According to the Maine Department of Conservation an "ice out" date is ". . . when you can navigate unimpeded from one end of the water body to the other. There may still be ice in coves or along the shoreline but when a person can traverse the entire water body without being stopped by ice flows . . ." the ice is considered to be "out". The Maine Department of Conservation provides charts depicting "Historic Lake Ice Out Data" on their website.