If you take the subway to 175th Street in Washington Heights (northern Manhattan), cross the George Washington Bridge into New Jersey, and take a right, you’re all of a sudden in the woods, running on dirt trails along the Palisades cliffs and spotting deer, hawks, and other runners and hikers. It’s great! I did 9.5 miles out at the Palisades last weekend and it was just lovely.
The trails aren’t quite as technical and the elevation doesn’t change as much as it will in the 50k on Bear Mountain, but it’s still a good workout and a nice change from running park trails. There’s no water available in the winter (and only a single water fountain I’m aware of in summer) so you need to carry whatever you need. There are two main trails – the Long Path along the cliff tops, and the Shore Path down by the edge of the river. I almost always stick to the Long Path, running an out-and-back, but I suppose going back and forth between the two on the handful of connector trails would give some good elevation gain. Maybe next time.