You can safely thaw a frozen turkey in two ways:   In cold water or in the refrigerator.    The cold water approach is faster, but requires a large container of cold water and that's probably your sink.   If you have enough space in your fridge and enough time, using the refrigerator may be the way to go since it keeps the turkey out your way, and away from any curious and hungry pets.

This chart gives thawing times for both methods.
 

Turkey Size In Refrigerator (about 24 hours per 4 to 5 pounds In Cold Water (About 30 minutes per pound)
4 to 12 pounds
(Serves 3 to 8 people)
1 to 3 days 2 to 6 hours
12 to 16 pounds
(Serves 8 to 11 people)
3 to 4 days 6 to 8 hours
16 to 20 pounds
(Serves 11 to 14 people)
4 to 5 days 8 to 10 hours
20 to 24 pounds
(Serves 14 to 16 people)
5 to 6 days 10 to 12 hours

Be sure to also check out our Turkey Roast Calculator for more thaw times, cook times, and more.