Thompson Park – Monmouth County

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Thompson Park - Monmouth

Hike through fields and forest around Swimming River Reservoir and Marlu Lake in Monmouth County.

6.7 miles, or less. Surface is mostly easy; some very prominent roots, especially in the beginning, and grassy areas can be quite muddy. Mostly flat, no big elevation changes.

Updated: 7/2020 Re-hiked, minor edits, added monarch photo. 11/2019 – Re-hiked, route adjusted to inner Reservoir Trail to go avoid torn up path along field edge. 11/2015Route changed to incorporate Marlu now that the bridge connects it to Reservoir, description updated, new photos.

Our two cents:

Nice park for short loops and easy strolls, plus a playground, ball fields, and even canoe and snowshoe rentals in season.

Multiple paths to cut this shorter. For the avid hiker, this is pretty mild but we were able to get a nearly 7 mile loop out of the trails so it is a good option if relatively nearby.

Lots of hiking along fields and not remote feeling. Navigating can be a tad difficult, see note on description below.


The trail map can usually be found in the trail kiosk, or print ahead from the park site. Follow along on your smartphone using our Interactive Map linked above.


Not in any books that we’re aware of.

Parking: N40.33085° W74.13978°

805 Newman Springs Road, Lincroft, NJ 07738. Detailed directions on the park site.

Note: There is another Thompson Park, in Middlesex County.


Porta-john in parking lot, and several more scattered around the park.

Hike Directions:

Overview: Reservoir Loop – Marlu Trail – Reservoir Loop – Thompson/Inner Loop

Note: Like most Monmouth County parks, on the trail map a BLUE SQUARE denotes moderate and a GREEN CIRCLE is easy – they aren’t trail markers or blazes. Junctions sometimes posts with the trail names on them but the trails themselves are usually not marked.

0.0 – Look for the trail kiosk at the end of the parking lot to pick up the paved Thompson Loop.

Thompson Monmouth trailhead

Shortly, when the paved Thompson Loop curves to the right, look for a BLUE marker post at the tree line at left. Walk LEFT towards that and enter the woods.

0.2 – At an area with a wide path (Track Loop), veer LEFT onto the trail.

0.4 – Just before getting to a view of the reservoir, the path turns RIGHT. Walk out to the view  first, then come back to the turn.

Approaching the reservoir
Swimming Lake Reservoir
Swimming Lake

Follow the trail as it hugs the reservoir, traveling above it. Part of the trail running closer to the water is now blocked off and you’ll be directed around.

Reservoir Loop trail
Reservoir Loop trail
Bridge on Reservoir Loop trail

1.2 – Where the trail becomes faint and overgrown – veer RIGHT uphill away from the water to the edge of a field. Turn LEFT for a few steps, then veer LEFT where the trail re-enters the woods.

1.6 – Come out into a clearing and parking lot. Cross the parking lot and start following the Marlu trail. A trail closer to the water parallels this trail.

Marlu Lake parking
Marlu Trail

1.9 – Veer RIGHT at an intersection. A wildlife blind is off to the left by the water.

The trail splits again shortly – keep RIGHT, then keep RIGHT again. At the field, turn LEFT to follow Marlu along field edges.

Marlu Trail follow field edges
Trail marker along Marlu

2.4 – The Marlu trail approaches the road, turns left, and ends at a bridge.

Bridge that connect Marlu with the Reservoir Trail
Reservoir Loop bridge
View from bridge

Just after crossing the bridge, turn LEFT to start following Reservoir Trail. Continue along the field.

2.7 – At a corner, take a few steps straight out-and-back to a bench with a view of Marlu lake.

Bench off of Reservoir trail

In a few steps, turn LEFT at a sign post indicating Reservoir Loop straight. Go over a wooden footbridge. Pass another wildlife blind off on the left.

3.0 – Turn RIGHT at an a T-intersection (with a signpost indicating to make a left). Turn RIGHT again on to the paved park trail.

3.1 – Turn LEFT back onto the trail (we noted no markers), then keep sharply left to continue on the trail as it goes between old wooden fence posts.

This area is unclear, missing the sharp left will lead you to the back of a house (Ranger Residence).

3.2 – Come out to a large open field. Follow the mowed/cleared path to the right, and then as it gently curves back and forth across the field towards a large house/park building in the distance.

The field seen in November then in July:

Cross this field on mowed paths
Mowed path through fields

Milkweed has been planted all across this open area. Monarch butterflies use this plant for food and to lay eggs on the underside of the leaves.

Monarchs were flitting all around as we hiked through the field.

Field of milkweed
Monarch butterfly on milkweed

3.7 – Reservoir Loop crosses a dual driveway lined with large trees. Continue on the path between the field and the edge of the forest.

Driveway lined with trees
Reservoir trail after crossing the driveway

4.5 – Keep RIGHT for a short out-and-back to a view of Swimming River Reservoir. Continue on the path at the edge of the forest, keeping RIGHT when encountering any splits in the trail.

Side trail to a view of the Reservoir again

5.1 – Arrive at a paved road near park buildings (Training Center, Friends of the Parks). Follow Reservoir Loop as it parallels the road for a short bit

Follow the paved road for a bit

5.3 – Turn RIGHT away from the paved road to follow Reservoir Loop on a mowed path along a field.

Back along the field trail

5.5 – Turn RIGHT and follow Reservoir Loop over a long bridge at Marlu Lake.

Long bridge

After the bridge, follow the paved Thompson Trail as it passes the Marlu Lake parking lot from earlier, and follow the paved Thompson Trail/Inner Loop back to the lot.
Hiked: 7/12/20.
Hiked: 11/10/19.
Hiked: 11/8/15.

Hiked: 11/20/11. Trail Blog: “Thompson Park – Swimming River Reservoir and Marlu Lake”