Where do reptiles such as alligators go when winter comes?

Source: Orlando Sentinel
While people burrow under mounds of warm blankets on cold winter nights, alligators also seek shelter from the cold. But in their case, muddy burrows provide warmth, and the beds they settle into are often on the side of a riverbank or at the bottom of a lake. Although they might disappear from sight for several days, alligators don't actually hibernate. Their metabolism slows down, and they breathe less often. But they seldom stay undercover longer than a week or two -- not long enough to be considered hibernation.
During times of dormancy, alligators live off their own fat, not needing to consume new food. But as soon as the sun comes out and the weather warms up, gators emerge from their dens to glide through the water and bask in the sun.
Occasionally in winter, alligators use a unique method to maintain body heat. They pile on top of one another in huge stacks of reptilian bodies. While the bottommost gators must gain massive amounts of heat from this precarious approach to generating energy, there is doubt that it benefits the reptile unfortunate enough to have landed on top of the pile.