Here is a good article on Mary Lee:
Great white shark returns to Myrtle Beach
She 'pings' a mark on the tracking map whenever her dorsal fin pops up out of the water. It's a satellite tracking device. So if she stays submerged for long periods, there will be long track segments. If she is on the surface, feeding for example, you will see more 'pings'. Looking at her entrance into Pamlico Sound through Ocracoke Inlet, you see that she appears to have hiked across the beach and island. What has happened is that she stayed completely submerged from the last ping out in the ocean, till she surfaced off Ocracoke harbor. Then she went back under, and back out through the inlet, surfacing again well up the beach toward Hatteras. Her last ping was about 1 this morning, well off Hatteras, out over the 50 fathom line. She's been doing a Run Silent, Run Deep ever since.