Usually not "swimming" per se, Williams' polar bears immerse themselves in bodies of water outdoors at all times of the year, especially in excruciating cold. It is a tradition and a kind of rite, from the walk across campus in the wee morning or dead of night, holding towels, all the way to shivering nakedness at the water's edge, thinking all the time about turning back.
The toughest polar bears have been known to break holes in ice that had formed on the river in the dead of winter, so that they could then jump in. So you think you're hardcore?
Getting to Polar Bear Swim
Outdoor bodies of water have a funny way of getting cold in the long Massachussets winters. Therefore, a polar bear swim can happen anywhere there is a safe, relatively clean and perhaps relatively secluded body of water. However, it is safer to go in a group, and the Outing Club runs regular swims for anyone interested in participating. Their most common destination is the Green River.
Some say you achieve official polar bear status when you have immersed yourself outdoors at least once each month, on a regular basis -- no planning for warm weather! Going with the Outing Club provides you with a regular schedule, friends who will watch out for you, encourage you, and perhaps fetch your sandals if they go floating down the river.
Surviving a Polar Bear Swim
Wear layers out to the site. Overdress. Have warm clothing for every part of your skin; don't neglect gloves, wool socks, thermal underwear, and especially a full hat -- one that covers the ears. Bring a large towel. Consider bringing strong sandals to wear into the water, such as Tevas -- this is a must if there is ice, as your feet will not be able to handle direct contact with the extremely cold river bottom.
As you remove your street clothes, arrange them with a thought to redressing quickly. Your hat should be the last thing to come off and the first thing you put on, then socks and gloves. Place all of these in safe, dry places, perhaps suspended from low branches.
When you get to the water, time your undressing so you are not standing in your skinnies for longer than you have to before immersing yourself. You will need to take off any clothing that gets wet afterwards or it will suck your body heat (while freezing into a cool shape). It is almost certainly best you don't wear clothing into the water.
When it is time, run into the water as deep as you can take it. Keep your head above water on cold days. Don't try to swim, and don't try to go in a little at a time, or you won't ever go in. Enjoy the thrill of being in the chill, and immediately run out and dry off very thoroughly before dressing.
Song of the Polar Bears
A little ditty is traditionally recited by the swimmers after they have undressed/changed into swimwear, and before they enter the water. The tune is the same tune as "Bingo" (B-I-N-G-O, and Bingo was his name-o). When everyone is ready, they sing together:
In, in, in we go
Through the ice and snow
Even though it's ten below
'cause we are polar bears.
. . . and as one they run into the merciless waters.