An Australian woman was injured after being hit by the tail of a whale shark while snorkeling in Ningaloo Reef.

The 29-year-old unidentified victim was swimming with a tour group Saturday, July 31, when she was struck. Responding St. John’s Ambulance said the woman suffered internal bleeding and upper torso injuries caused by “the crush,” according to the BBC.

The woman was treated in the town of Exmouth and was later flown to a hospital in Perth, where she was said to be in a “serious but stable condition” Monday, Aug. 3.

Swimming with whale sharks is a popular tourist activity off the Ningaloo coast, the country’s popular tourist destination, every year between March and July. Known to be the largest fish species in the world, whale sharks are typically docile and harmless to humans despite belonging to the shark family.

Western Australia Police said other guests of the snorkeling tour escaped the encounter uninjured. The group had been only about a few hundred meters from the shore when the incident happened. Safety regulators were investigating the incident.

Ningaloo reef, spanning nearly 187 miles, is regarded to be the world’s largest coral reef and the home to a huge diversity of marine life, including whale sharks that are the major draw for tourists.

In another incident involving sharks, a Maine woman was killed last week in what was believed to be an attack by the predator near Bailey Island. The state’s Department of Marine Resources said, based on the reports by witnesses, the woman was swimming off the coast when the suspected shark attack happened. Nearby kayakers brought the woman to the shore and Emergency medical responders pronounced her dead. The Marine Patrol cautioned swimmers and boaters to avoid the area near seals or schooling fish as sharks tend to appear to feed on them.

Snorkelers swim with a six meter whale shark just outside Hanifaru Bay of Maldives’ remote Baa Atoll, August 11, 2011. Photo: REUTERS/David Loh