Outdoor heaters, fire pits, and even blankets are commonly used to create a warm atmosphere. At Mile Marker One restaurant overlooking the Annisquam River in Gloucester, patrons have been enjoying outdoor dining all winter long in a series of snug, heated waterfront igloo domes, noshing on hearty winter menu items, enjoying cocktails and wine, and private-dining style service while looking out on the sleepy docks of the Cape Ann Marina. It’s creative, delicious and beautiful—not to mention fun.