Mary Lee has logged more than 16,000 miles in the past two years. She's been to Florida, Bermuda and Cape Cod.
She's not a beach bum, though. Mary Lee is a 3,456-pound great white shark. You wouldn't want to run into her in the surf, but you can follow her on Twitter and track her movements online. She's one of five great white sharks along the East Coast of the United States that is actively "pinging" her location via satellite transmitter. An online map tracks the sharks' courses as they go, so you can see nearly real-time data.
But there's no coast-is-clear guarantee for fearful late-summer swimmers. The trackers only ping when the animals surface, and sharks don't have to surface to breathe. And of course there are more than five out there.
Swimmers were evacuated from the beach after a 12 to 14 foot great white shark was spotted off the coast of Massachusetts.
And use common sense.
"Don't go play with the seals in the water at dawn or dusk. Other than that, enjoy life, go swimming. Because if you're worried about a shark interaction, you should be scared to death to get in the car," says Chris Fischer, founder and expedition leader of Ocearch, the research and educational nonprofit that tagged and tracks Mary Lee and other sharks.
There were 47 attacks in the United States in 2013, with one fatality in Hawaii.
Compare that with more than 33,000 fatal vehicle crashes in the United States in 2012, the last full year for which figures are available. In the first half of 2013, more than 15,000 motor vehicle traffic fatalities are estimated, according to the National Highway Traffic Safety Administration.
"If you're the kind of person who's scared of sharks and wants to know if there's one around you, there's no technology for that," says Gregory Skomal, a biologist with Massachusetts' Division of Marine Fisheries who has tagged sharks with Ocearch.
Still, the GPS transmitters with wet-dry switches that are activated when the sharks surface provide a pretty interesting picture.
Lydia has covered a lot of water since she was tagged in March 2013. Her movements are logged on Ocearch's shark tracker.
On Ocearch's online tracker you can see each shark's tangle of pings over several years, tracing their movements over thousands of miles.
Skomal has been researching sharks for more than 25 years and has teamed up with Fischer and Ocearch three times in the past few years to tag great whites along the East Coast. He's tracking Mary Lee, Lydia, Katharine, Genie and Betsy.
Lydia is a real world traveler. "Lydia is an exciting shark. Lydia makes it look like Mary Lee is a real homebody," Skomal said. Lydia was tagged in March 2013 and has already logged more than 25,000 miles.
Over the last six years, Skomal has tagged more than 40 great white sharks using various tracking devices. The five tagged with Ocearch provide real-time tracking, while other trackers offer data after they detach from the shark.
Fischer, who is not a biologist, has led more than 20 research expeditions with scientists around the world since 2007, tagging about 80 great white sharks in total.
Ocearch gathers data and tags sharks and other marine predators by taking them out of the water for about 15 minutes using a custom lift. That ability to lift sharks weighing thousands of pounds out of the water to attach tags that track their movements in real-time is what distinguishes Ocearch, Skomal says.
Some of the sharks also have Twitter accounts.
"Every time a shark decides to set up its own Twitter account, it's not really up to us. We don't decide that," says Fischer. It's a personality thing, he joked.
Mary Lee tweets occasionally, while Katharine, who's in her late teens, is a "chatterbox" with more than 16,000 followers. The real identity of the tweeters is a mystery. "People were inspired to give these sharks voices, and we don't know who they are," Fischer said.
Fischer credits the publicly shared shark tracker and the power of social media with helping to change the tone of the conversation around sharks.
After all, they're king of the sea, and the marine ecosystem depends on them.