Lyngbakr is the name of a massive whale

Whale

Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...

-like sea monster

Sea monster

Sea monsters are sea-dwelling mythical or legendary creatures, often believed to be of immense size.Marine monsters can take many forms, including sea dragons, sea serpents, or multi-armed beasts. They can be slimy or scaly and are often pictured threatening ships or spouting jets of water...

 reported in the Örvar-Odds saga

Saga

Sagas, are stories in Old Norse about ancient Scandinavian and Germanic history, etc.Saga may also refer to:Business*Saga DAB radio, a British radio station*Saga Airlines, a Turkish airline*Saga Falabella, a department store chain in Peru...

 to have existed in the Greenland Sea

Greenland Sea

The Greenland Sea is a body of water that borders Greenland to the west, the Svalbard archipelago to the east, Fram Strait and the Arctic Ocean to the north, and the Norwegian Sea and Iceland to the south. The Greenland Sea is often defined as part of the Arctic Ocean, sometimes as part of the...

. According to the saga, Lyngbakr would bait seafarers by posing as a heather-covered island, and when a crew landed on his back, he sank into the sea, drowning the crew. Lyngbakr is best explained scientifically as a vanishing island

Vanishing island

Vanishing island refers to any permanent island which is exposed at low tide but is submersed at high tide. Vanishing islands occur globally. There are seven vanishing islands in the Philippines and several in the San Juan Islands.-Cryptozoology:...

.

Örvar-Odds saga

As Örvar-Oddr and his crew were sailing southwesterly through the Greenland Sea, the deck officer Vignir knew this area would be dangerous, and made Oddr agree to sail the ship beginning the next day, to which Oddr requested Vignir advise him. As they sailed, they spotted two rocks which rose out of the water. The presence of these rocks puzzled Oddr. Later, they passed by a large island covered in heather. Curious, Oddr made up his mind to turn back and send five men to check out the island, but as they approached where the island had been before, they saw that it and the two rocks vanished.

Vignir explained to Oddr that, had they landed sooner, the crew would have surely drowned. The "rocks" and "island" must have been two sea monsters-- Lyngbakr, the greatest whale in the world, and Hafgufa

Hafgufa

Hafgufa is the name of a massive sea monster reported to have existed in the Greenland Sea which was said to disguise itself as an island or pair of rocks rising from the sea...

, who bore all the monsters in the sea. The rocks had surely been the nose of Hafgufa; the island, Lyngbakr; Ögmundar Eyþjófsbana had allegedly summoned the beasts to kill Oddr and his men.