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 separate bowl.
Immerse 4 or 5 scallops in the bowl of buttermilk. Transfer to the flour mixture; roll around until thickly coated.
Lower scallops gently into the hot oil. Cook until golden and crispy, 3 to 4 minutes. Drain on a plate lined with paper towels. Repeat with remaining scallops.