There’s a claim in this document that it was “175 miles” out:
http://www.grdodge.org/Downloads/h20book/05.H20.Land.81-1124.FA.pdf
and the New Jersey legislature apparently believed the same (the folks above snatched it from their bill):
http://www.westmilfordnow.com/highlandsdraftbill.htm
(There are a couple of places the draft bill above appears on the web, all pretty much identical to the above.)
But that’s as far back as I could get with my meager Googling skills (I could swear I’ve seen the same claim printed somewhere…). Hope you find what you need!
Edited to add:
I found a link with this reference:
“This place, Long Island, that in 1609 Robert Juett, who was Henry Hudson’s first mate, exclaimed as his ship, the Half Moon, slipped in New York Harbor, “we found a land full of great oaks, with grass and flowers, as pleasant as ever has been seen.” Daniel Denton, 61 years later had this to say, “The greatest part of the Island is very full of Timber, as Oaks, white and red, Walnut-trees, Chestnut-trees, which yield store of mast for swine…also Maples, Cedars, Saxifrage, Beach, Birch, Holly, Hazel, with many sorts more…the Countrey itself sends forth such a fragrant smell that it may be perceived at Sea before they can make the land.””
It’s here: http://www.pinebarrens.org/publications/this_place.php
Maybe you just need to find a good reference to Daniel Denton somewhere . . . The above quote may have come from the document someone’s posted here:
http://www.dentongenealogy.org/Brief%20Description%20of%20New%20York.htm