There is 25 miles of trails in the park, wooded (very natural setting), flat to rolling terrain. A dirt road (closed to cars) runs the length of the park. There are maps displayed at trailheads. Great place. Park outside 64th street gate and you'll not need to pay entry. Very popular place on a weekend.
Access is entirely through NWR; by foot, bike, or summer via trolley. To get to this park you have to traverse the 6-mile length of Back Bay NWR, then many miles of trails to explore in the park. Take plenty of water, gets very hot & buggy in summer. Terrain is Flat, several sandy sections in park, and access is limited to the beach in the winter (NWR closes other trails, so not to disturb waterfowl, please observe).
Tidewater Striders is the local running club (627-RACE), very helpful.