I'm looking for romantic day trip ideas from NYC using public transportation? Preferably to an area with a lake and some hiking? Also, any campgrounds that rent out tents etc would be great.

I realize this is vague. Just trying to get some ideas. I thought of Fire Island but really would like an area with a lake.

You might want to check out Bear Mountain.

What about Cold Spring on the Hudson River? It's a big kayaking center and hiking in the area. Take the Hudson line of MetroNorth directly to Cold Spring.

http://www.hvgateway.com/cs00.htm

Thanks for the suggestions.

I have actually been to Cold Spring and loved it so prefer a new place this time around. The train ride there itself was gorgeous.

Is Bear Mountain accessible by train?

Unfortunately, only by the Hudson line across the river. Just found this info at hudsonriver.com:

Getting There
The park is located about 50 miles north of New York City at the intersection of the Palisades Parkway and Route 9W. Rail commuters can take Metro-North to the Peekskill or Garrison stations and take a taxi across the river to the park. A taxi runs up to $25 one way.

You really need a car for Bear Mt - since you may be able to get a cab at Peekskill - but you would have to arrange a cab back in advance.

Also - I'm not at all sure Beat Mt is romantic. It;s usually full of families - or troops of school kids in season.