"When the Dutch finally ceded New Netherlands to the English in 1674, they left behind a legacy of place names—'toponyms,' to use the technical term. The English, whether to avoid confusion or from lack of interest, kept many, though often in Anglicized form. Thus Breuckelen became 'Brooklyn,' Vlissingen became 'Flushing,' the Bouwerij became the 'Bowery,' and so on. Of all these descendant names, one stands out as particularly forbidding, and the ambiguity of its true meaning has invited all kinds of mythical associations and claptrap. This is 'Hell Gate,' which denotes the churlish stretch of the East River between Manhattan and Astoria, Queens, at the nexus of the 'Y' formed by the East River to the south and to the northeast and the Harlem River to the northwest..."
For more on Hell Gate, check out this article by Michael Nichols in Gotham: A Blog for Scholars of New York City History.