A mysterious island has manifested in the Bermuda Triangle and authorities are warning locals and curious cruise passengers to stay away as the shifting land-mass is surrounded by dangerous currents and sharks.

Nicknamed Shelly Island by locals because of the large number of shells on it, the mile-long sand bank appeared over the last couple of months just 45m off Cape Hatteras in North Carolina.

Surrounding the waters of the so-called Devil’s Triangle, the new island measures around 1.6km long and more than 121m wide, Virginian Pilot reported.

However people are being told to stay away because of strong currents in the gap separating the sandbank from the mainland.

Bill Smith, president of the North Carolina Beach Buggy Association, said: ‘We’re worried about shark bites, but we’re more worried about drownings.’

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The future of the island is not clear. The sandbank could continue to grow and form part of Cape Point, or it could vanish as quickly as it appeared.

Although the image is striking and the mystery island’s location within the Bermuda Triangle gives it a good media angle, the ‘island’ is in fact a shoal “a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material, and rises from the bed of a body of water to near the surface” according to Wikipedia.

The mysterious Shelly Island appears to be a longshore bar, formed by offshore moving bottom current depositing sand where the current reaches the wave break, this is why the ‘island’ is covered in shells.

White Island, a small horseshoe shaped land mass 1.4 kilometres off the northern shore of Mambajao in the volcanic island of Camiguin in the Philippines is another example of this.

Shelly island picture courtesty Chadonka on Instagram.