BEACHGOERS have been left on high alert after a dangerous apex predator was spotted off the coast of a popular surfing destination.

The large tiger shark was detected on Monday near Kauai, the northernmost island in Hawaii.

It was seen swimming around Hanalei Bay, which includes a popular surfing spot known as “The Bowl,” Surfer reported.

That prompted officials to close many beaches on the northern side of the island until further notice.

This notice came just days after Kevin Kanehe, 50, was attacked by a 12 to 15ft tiger shark while surfing in the bay on October 15.

Kanehe was badly mangled by the predator, but managed to fight the beast off by sticking a finger into its nostril.

He made it back to the shore with the help of another surfer named Jeff McBride.

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“The bite went to the bone above and below his knee, taking some chips off his femur, knee cap and tibia,” Kanehe wife Deanna said on a GoFundMe page raising money for his medical expenses.

“He sustained serious injuries to his leg and hand,” she added.

“Kevin is currently undergoing his second surgery and remains in the hospital. Doctors are predicting up to a year recovery process.

“He his knee was torn up pretty bad and into his joint too. There is still concern for infection.”

So far, the campaign has raised $82,326, which is more than its original $75,000 goal.

Another dangerous animal was detected off the coast of Kauai on Monday.

A dangerous Portuguese Man o’ War jellyfish was spotted between Poipu and Kekaha on the southern side of the island.

This prompted officials to advise against swimming or surfing in those waters.

Another Kauai resident named Bethany Hamilton, 33, lost her arm in a vicious shark attack while surfing two decades ago.