The Merrimac is a river located in the northeastern United States, primarily flowing through the state of New Hampshire and into Massachusetts. It is approximately 117 miles long and is known for its scenic beauty and recreational opportunities, including fishing, boating, and hiking along its banks. Historically, the name Merrimac is also associated with the famous Civil War ironclad warship, the CSS Virginia, which was originally named the Merrimack. This ship is notable for its role in the Battle of Hampton Roads in 1862, where it engaged in a historic naval battle against the USS Monitor.