Swimming River Reservoir/Marlu Lake Loop


This hike loops around the Swimming River Reservoir and Marlu Lake, passing many century-old trees.

3.5 hours
6 miles
Route Type:
Allowed on leash
Views, Woods
First Published:

Daniel Chazin


Crossing the dam at Marlu Lake. Photo by Daniel Chazin.


View Thompson Park in a larger map

Trailhead GPS Coordinates
Driving Directions

Take the Garden State Parkway South to Exit 109 (Red Bank/Lincroft). Turn left at the end of the ramp onto County Route 520 West and continue for 2.3 miles to the entrance to Thompson Park (the entrance is 0.3 mile beyond the traffic circle at the entrance to Brookdale Community College). Turn left into the park, continue past the first parking lot, and turn left into the Old Orchard parking lot.


The 667-acre Thompson Park is a former horse farm, bequeathed in 1968 to Monmouth County by Geraldine Thompson. For most of the way, this figure-eight hike follows the Reservoir Loop, which loops around the Swimming River Reservoir and Marlu Lake. Although this trail is officially blazed blue, blazes are found only occasionally (on signposts, mainly at junctions), and there are no blazes at many important junctions. You should obtain a trail map before beginning the hike (maps are available online at www.monmouthcountyparks.com or from a kiosk at the trailhead). Keep in mind, however, that the trail is not always accurately shown on the map, and be sure to pay careful attention to the directions in the hike description.

The trails in this park are open to joggers, bicyclists and equestrians. The park brochure indicates that the Reservoir Loop is rated as “moderate”; however, the rating system is designed primarily with bicyclists in mind. The hike has no significant changes in elevation and mostly follows well-graded paths. Portions of the trails can be muddy, however, and hikers should wear waterproof hiking boots.

From the kiosk at the southeast corner of the Old Orchard parking lot, turn right (south) on a paved path. Follow the paved path across a grassy area, passing a wooden shelter on the left. In about 500 feet, as the paved path curves to the right, you’ll notice a tree on the left, with a vague dirt path heading towards the woods. Follow this path for about 150 feet to the edge of the woods, where a post on the left marks the start of the Reservoir Loop.

Continue ahead, down a switchback, and cross a stream on a wooden bridge. Just beyond, bear left at a fork to continue on the Reservoir Loop. A short distance ahead, the Track Loop joins from the right, but the trails run jointly only for about 25 feet. When they diverge, turn left to continue along the Reservoir Loop, which now descends towards the Swimming River Reservoir. The trail turns right just before reaching the reservoir, but you should continue ahead to a viewpoint over the reservoir.First View of reservoir. Photo by Daniel Chazin.

After taking in the view, return to the main trail and turn left (northwest). The Reservoir Loop now closely parallels the reservoir, with views through the trees on the left over the reservoir. The footing can be a little rough in a few places, where you traverse an area covered by tangled tree roots. North section of Reservoir Loop Trail. Photo by Daniel Chazin.You’ll pass many huge trees, over a century old, and cross several wooden bridges. Several side trails lead to the right, but you should continue ahead on the path that parallels the shore of the reservoir. This is a particularly beautiful trail section.

After a while, you’ll notice another wide trail on the right – the Track Loop. The two trails closely parallel each other for some distance, but they do not converge. A few hundred feet beyond where the Trail Loop turns right, away from the Reservoir Loop, you’ll cross a small stream and reach a fork, with three closely-spaced tall trees ahead on the left. You should take the right branch of the fork, bearing to the right of the tall trees and up a short incline, and continue ahead until you emerge onto the edge of a field.

Turn left and skirt the edge of the field for about 75 feet, then bear left onto a dirt path that continues to parallel the reservoir. As you approach the northwestern end of the reservoir, it becomes a marshy, reed-filled area and then a meandering stream.

About a mile and a half from the trailhead, the trail curves to the right and reaches a paved path. Turn left onto this paved path, which passes the Marlu parking area. Soon, you’ll approach the southern tip of Marlu Lake and pass a “Park System Vehicle Only” sign and a post with a trail marker for the Reservoir Loop. Continue ahead on the paved path, which crosses the earthen dam of Marlu Lake. At the end of the dam, you’ll notice another post with a trail marker. Turn right at this post and follow a dirt path along the edge of an open field.

At the next post, the trail turns right and heads into the woods. It continues to parallel Marlu Lake, which is visible through the trees on the right. When you reach a T-intersection, turn right to continue on the Reservoir Loop. The next section of the trail is often quite muddy.

After traversing a marshy area (where the trail has recently been rerouted to a drier treadway), the trail crosses a wooden bridge and bears right. A short distance ahead, the trail curves to the left, with a bench on the right, overlooking the lake.

Just beyond, you’ll come to a Y-intersection. Bear left here, following the sign for the Reservoir Trail, and continue on a mowed path Crossing the long field between the two trail sections. Photo by Daniel Chazin.along the left side of a field. When you reach a fork, with a rutted track heading straight ahead and a mowed path bearing right, follow the mowed path, which continues to run along the left side of fields, making several turns. This trail section can also be muddy.

         With Longbridge Road visible beyond a field on the right, the trail turns left, passing between two trail marker posts, and reenters the woods, with large trees on either side of the trail. It follows a wide, grassy woods road which meanders through the woods. Soon, you’ll notice the brick-and-concrete ruins of a building in the woods on the right. Just beyond, bear right at a fork to continue on the trail.

         Soon, the trail crosses a paved path diagonally to the left. About 50 feet beyond, turn left onto another wide, grassy path. In a short distance, you’ll pass an abandoned wooden building on the right and emerge onto an open field. Continue straight ahead and follow a winding grassy path through the middle of the field for about half a mile. You’ve now reached the midpoint of the hike.

         Towards the end of the field, with Longbridge Road visible directly ahead, turn left onto a slightly narrower grassy path. A short distance beyond, you’ll cross two paved roads, with a white frame building (now used for the park’s Historical Services) visible on the left. As you cross the second road, an arm of the Swimming River Reservoir comes into view on the right. You’ll be paralleling this arm of the reservoir for the next section of the hike.

         Continue ahead on the wide path, between open fields on the left and woods on the right, with views of the reservoir through the trees. You’ll pass some more park buildings on the left, after which woods appear on both sides of the trail. As you near the end of the peninsula that juts out into the reservoir, a narrower path goes off to the right.  This short path leads to a dead-end at a viewpoint over the reservoir, and you should continue to follow the wider path, which loops around to the left and soon begins to head northwest. Across the reservoir, you can see (through the trees) the trail that you followed earlier in the hike (note the wooden bridges along the trail).Bridge along the southwestern side of the northern arm of Swimming River Reservoir. Photo by Daniel Chazin.

         In a third of a mile, you’ll reach a Y-intersection, where you should bear right to remain on the trail, which now parallels the reservoir more closely. When the trail reaches a paved road that comes in from the left, continue ahead on the paved road, parallel to the reservoir, for about 750 feet, then bear right at a trail marker post and continue along a wide, grassy path. Soon, the trail bears right onto a dirt path bordered by logs and crosses two wooden bridges.

         A short distance beyond, you’ll reach a paved path near the southwest tip of Marlu Lake. You’ve now completed the loop portion of the Reservoir Loop. Turn right, follow the paved path over the dam (now retracing your steps from earlier in the hike), and continue until you reach a paved circle just beyond the Marlu parking area. Turn left at the circle onto another paved path, which heads across a field.

         When you reach a fork, bear left. Soon, you’ll approach a paved road, with the park’s Creative Arts Center visible beyond. Follow the paved path as it curves to the right and parallels the road, passing the Theater Barn and other park buildings. The paved path ends at the Filly Run parking lot, but you should continue ahead on a wide dirt path (not shown on the park map). The dirt path soon reaches a paved path which comes in from the right. Continue ahead on the paved path, which curves to the left and returns to the Old Orchard parking lot, where the hike began.