For San Francisco tourists, Aquatic Park Cove is one of the city's most iconic areas, a popular spot to watch enormous sea lions and harbor seals frolicking in the water across from Ghirardelli Square.

For locals - or those who can brave the brisk waters, in any case - the cove is known as one of the best places for an open-water swim, especially favoured by triathletes.

But last week, the cove's most prominent features clashed in a harrowing manner, when "aggressive" marine mammals attacked three swimmers in the span of about five days, officials said.

The incidents prompted the National Park Service, which runs the cove, to temporarily ban swimming there over the weekend. On Friday, Park Service workers posted signs around the water that warned of the recent attacks: "Danger. Aquatic Park Cove Closed for Swimming Due to Multiple Marine Animal Bites."

Early in the week, an unnamed member of the South End Rowing Club was bitten while in the cove but did not require treatment, according to the San Francisco Chronicle.

On Thursday afternoon, a sea lion bit 56-year-old Christian Einfeldt in the right arm while he was swimming about a quarter-mile from the cove's shore, KTVU News reported.

"I turned around and I saw a large male bull sea lion (a few feet away), and I became very concerned," Einfeldt, a lawyer who has been swimming in the cove for two years, told the news station from the hospital.

Einfeldt said that he tried toward off the animal by shouting "No!" but that the sea lion continued to approach.

"His head kind of actually slid down my arm because he was still coming forward," he added. "Fortunately he only got one tooth into my arm."

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Bleeding, Einfeldt flagged down a nearby sailboat and was taken to a hospital with non-life-threatening injuries, the news station reported. The San Francisco Fire Department said it applied a tourniquet to Einfeldt's wound at Pier 45, which probably saved his life.

"I'm lucky to be alive," Einfeldt told KTVU. "I'm happy to be alive right now."

Less than 24 hours later, a third swimmer was attacked.

On Friday morning, Rick Mulvihill was bitten in the groin area by a marine animal while in a part of the cove known as "the Jacuzzi," the Chronicle reported.

"It hit him right here, close to the family jewels," Bob Roper, a fellow member of South End Rowing Club, told the newspaper while pointing to the inside of his upper thigh. "I've been here 50 years, and I've never heard of anything like this. You have a lot of very, very nervous swimmers now, and I don't blame them. It's pretty bad when you get bit by a seal."

Other swimmers reportedly pulled Mulvihill from the water to safety. He was taken to a hospital with a "severe bite," according to a San Francisco fire spokesman.

Though Roper identified the animal that bit Mulvihill as a seal, officials told the Chronicle it can be difficult to distinguish between sea lions and harbour seals. Both species appear in Aquatic Park Cove, and both have been known to bite people occasionally in the San Francisco Bay.

Such attacks happen so infrequently, however, that the South End Rowing Club characterises them as "rare" on its website in response to questions about the dangers of swimming in the bay. (The club notes that boats and hypothermia are more dangerous.) Representatives for the club, as well as for the Dolphin Club, a similar group, did not immediately respond to interview requests Saturday morning.

Officials said it was unclear whether the same animal was responsible for all of the attacks. The cove will be closed to swimmers until Monday as park officials work on a safety plan, they said in a statement.

"It's really hard to speculate why this interaction happened," Shawn Johnson, a veterinarian with California's nonprofit Marine Mammal Center, told KTVU. "But any time you're interacting with a wild animal, there's a possibility of getting bit."

In May, officials in Steveston, British Columbia, issued numerous warnings after a video captured a California sea lion dragging a young girl into the water by her dress near the Steveston Fisherman's Wharf.

As The Washington Post's Kristine Phillips reported, the girl was rescued. Video leading up to the incident showed a crowd on the dock gathered dangerously close to the edge, some feeding the animal. Despite the warnings, officials said, the incident seemed to attract even more curious onlookers who wanted to spot the sea lion.

"Sometimes, you got to give your head a shake," Bob Baziuk, general manager of the Steveston Harbor Authority, told Canadian Broadcasting Corp. News. "Steveston's going to be synonymous with the 'Jaws' theme pretty soon. You have a hungry animal, and these people are dumb enough to feed it."