The Long Path hiking trail passes through salt marshes along the Hudson river, and reaches a height of up to 4000 feet. Its 326 miles (525 km) lie in New Jersey and New York.
Introduction by the New York-New Jersey Trail Conference.
Pretty recent information.
Jacob Aronson devotes his blog entirely to the Long Path. Read his day to day account.
Account of a thru-hike of the Long Path, on trailjournals.com.
A bit outdated (2004) website, but some information might provide useful.