From A Wiki of Ice and Fire
The Shivering Sea is a frigid sea north of Essos. It is bounded to the west by Westeros, to the south by Essos, to the north by a vast frozen wilderness called the White Waste, and to the east by lands and seas unknown.
Braavos is located in a lagoon in northwestern Essos where the Shivering Sea meets the narrow sea. East of Braavos are the islands of Lorath and Lorath Bay. Further east is the Axe and the oft-disputed Bitterweed Bay. Next along the Shivering Sea are the delta of the Sarne, the Kingdom of Omber, and the Bay of Tusks. East of the latter bay is the forested Kingdom of the Ifequevron, north of which are the islands of Ibben. The Realm of Jhogwin lies between the Shivering Sea and the Krazaaj Zasqa. Even further east are Leviathan Sound, the Thousand Islands, N'Ghai, and forested Mossovy. It is unknown how far east the sea extends beyond Mossovy.
Tales and myths
There are several tales about the Shivering Sea, including queer lights shimmering in the sky, where the demon mother of the ice giants dances eternally through the night, seeking to lure men northward to their dooms. Tales also mention Cannibal Bay, where ships enter only to find themselves trapped forever when the sea freezes behind them. Other tales also mention pale blue mists moving across the waters, so cold they freeze any ship they pass over; drowned spirits that rise at night to drag the living down into the depths; or mermaids of pale flesh and black-scaled tails, far more malign than their sisters to the south.
The waters of the Shivering Sea teem with life. Hundreds of varieties of fish swim through its depths, including salmon, wolf fish, sand lances, grey skates, lampreys and other eels, whitefish, char, shark, herring, mackerel, and cod. Crabs and lobsters are found everywhere along its shores. Seals, narwhals, walruses, and sea lions have their rookeries and breeding grounds on and around the countless rocky islands and sea stacks. The sea is also home to many whales, including grey whales, white whales, humpbacks, spotted whales, and leviathans. The westernmost reaches of the Shivering Sea, from Skagos and the Grey Cliffs to the delta of the Sarne, are the richest fishing grounds in the known world.
References and Notes