On the first Sunday in January, I pull into the Empire Village Beach parking lot to meet 10 neighbors for a swim. The air temperature is 35 degrees Fahrenheit; Lake Michigan is 37 degrees. The group is made up almost entirely of women with members spanning in age from their early 30s to 70 years old. Most of the people present this first Sunday in January, myself included, have been meeting once or twice weekly for cold water swims since October. Winter swimming, also called cold dipping or polar plunging, is an umbrella term for various ways of submerging in cold water. For this group of brave locals, cold dipping involves a measured entrance into Lake Michigan, partnered with calm breathing. Participants spend 3-5 minutes in the water up to their shoulders, often wearing neoprene booties and gloves to fight against numbness in their extremities. Most of us wear winter hats on our heads and do not go under, though a few brave souls will wear swimming caps and plunge their entire bodies under the waves.