Heat oil in a deep fryer or large saucepan to 400 degrees F (200 degrees C).

Pour buttermilk into a bowl. Combine flour, salt, and pepper in a second bowl. Dip 4 or 5 scallops in buttermilk, then roll in flour mixture until thickly coated.

Cook coated scallops in hot oil until golden and crispy, 3 to 4 minutes. Drain on a paper towel-lined plate. Repeat coating and frying remaining scallops.