USCGC Mobile Bay (WTGB-103) is an active icebreaking tug under the direction of the United States Coast Guard.

She is one of two ships in her class that has been equipped with a 120-foot (37 m) aids-to-navigation (ATON) barge operating on the Great Lakes.

During the winter months, Mobile Bay detaches from the ATON barge and is largely responsible for ice breaking in the Northern Great Lakes in order to maintain an operable level of maritime commerce in the region.

At this time, the cutter will replace the buoys set in the fall with the traditional channel markers, since the winter months will have ended.

The cutter will also inspect year round buoys to ensure they are positioned correctly and watching properly.