In the books
In the A Song of Ice and Fire novels, the Sea of Sighs is in the same location, in what is known as the Lands of the Long Summer. The "demon road" that passes through Mantarys on its way from Volantis to Slaver's Bay runs along its northern shore, but the road is considered cursed and few dare to use its perils - most preferring the sea route south around Valyria itself.
It is not known if the Sea of Sighs existed before the Doom of Valyria, or was created during the volcanic tumults of that event. The latter seems more likely, as the map collection The Lands of Ice and Fire reveals that the Sea of Sighs appears to be colored blood-red, suggesting an ominous history. Map artwork from the Histories & Lore for Season 1 depicted the Sea of Sighs as existing before the Doom - but this may have just been an assumption by the artist. It is also possible that the sea was befouled somehow by the Doom, and it wasn't always blood-red, and perhaps used to have a different name.
Seas of the Known World
|Lesser and Inland Seas:|