The species was not confirmed but local reports suggested it was a bull shark.
Her horrified husband rushed into the water in the hope he could drive the shark away before it could strike again.
Tourists gathered around the victim and used their clothes to stem the bleeding.
Video footage captured by another tourist showed the shark in the vicinity ahead of the attack.
It is understood that it had been swimming in the area for around 40 minutes before striking.
“The shark was estimated to be approximately 6ft [1.83m] in length. However, the species is yet to be confirmed. It has been determined that the tourist had attempted to engage with the animal from the shallows in an attempt to take photographs,” the authorities said.
Shark attacks rare in Turks and Caicos
Shark attacks are rare in the Turks and Caicos, with only one reported last year.
Nevertheless, authorities in the Caribbean have urged caution.
In the Cayman Islands feeding sharks has been illegal since 2022 because of the risk to swimmers and divers.
“Some people believe feeding sharks is great for business or will increase tips from customers, and some even mistakenly believe that conditioning sharks to take speared lionfish will somehow teach them to hunt lionfish out of reef crevices. But teaching sharks to take food from divers only really endangers both humans and sharks,” the Cayman authorities warned.
It is estimated around 83 people a year are the victims of unprovoked shark attacks.
In some parts of the world shark attacks are on the rise, notably off the coast of southern Australia and the US eastern seaboard.
In July 2020, Julie Dimperio Holowach, 63, of New York City, was killed by a shark while swimming off the coast of Maine.
According to the International Shark Attack File, the increase is due to the number of people entering the water.
“The more sharks and people there are in one place, the greater the chance of them bumping into each other,” said Gavin Naylor, director of the Florida Programme for Shark Research.