Virtually all New Yorkers, I expect, know the name "Gowanus" via the Gowanus Canal in Brooklyn. Likewise, I expect that most New Yorkers don't give the name a second thought, as odd as it is. If I thought about it, I probably would have guessed that it derived from an eponymous Dutch farmer or something.
In fact, the derivation seems uncertain. This article suggests that it derived "either from Gowane, a Canarsee tribe leader, or the Dutch word for bay, gouwee."
But Ron Chernow, in Washington: A Life, suggests that Gowanus has nothing to do with Gowane, gouwee or my hypothetical dutchman, referring to "a wooded, hilly area [of Brooklyn] called the Heights of Guana (or Gowanus Heights)."
No word on who or what Guana was. I'm glad we cleared that up.