When you spend time near the shoreline in Maine you will likely see a Common Watersnake (Nerodia sipedon). If you do, don't panic, or even worry, they are not poisonous. They are also known by a variety of common names, including Northern Watersnake.
Sometime they can be seen sunning themselves on a log, since being reptiles they are cold blooded and have to absorb heat from the sun. You can also find them away from the water, and if one can get over the initial fright of seeing a snake, one can marvel at their beauty.
As they get older they become darker in color and may even appear to be black.
Usually they are seen swimming along the water's edge looking for small critters to eat.
It is best to simply leave them alone and let them go about their business.