Mamcoke Island

Connecticut State College Arboretum Park

40.5 acres in Waterford, CT

Parking: Small pull off near 44 Benham Ave Quaker Hill, CT

Trail Map               Trails: 2.5 miles           Rating: ★★☆☆☆

Mamacoke Island is a a sensitive natural conservation area and is designated by the Audubon Society as an Important Bird Area by the national Audubon Society.  While wonderful to explore, usage by running, mountain bikes, or dogs is actively discouraged.  The island masquerades as a peninsula most of the time, separated from the mainland by a brackish marsh. The marsh is almost always passable (the tide has to be extremely high). This area is used mainly for its educational opportunities by Connecticut College and the trails here appear to be rough and sparsely maintained.


From the small pull-off along Benham Ave the trails start on wide paths in open fields that were once pastures and orchard of the Mamacock Farm.  To reach the island head towards the far back right of the fields and you’ll approach private property.  The trail will head down to the train tracks which you walk along briefly until reaching a small gap with signage for the island.

The marsh crossing was muddy on my last visit though easily passable and once entering the tree line on the island the trail splits into a loop.  I headed right and the trail followed a rock wall at a distance before climbing up a short slope.  This brings you up on top of the rocky knob though no trail leads to the island’s highpoint (which supposedly features a large glacial erratic) at 123′ above sea level.  I was itching to explore the central summit, but protecting the sensitive area gets priority.

Towards the northern tip of the island the trail finally meets the water on a rocky jut for views of the Thames River and the Naval Sub Base.  Heading back towards the original fork to complete the loop guides you along a long tall vertical cliff face. Total distance is about a half mile.

On the mainland there is a small network of trails that add up to two miles or so in the Matthies and Avery Tracts.  These trails are wide and easy to follow through the hilly terrain. Not much to note but they seemed to be popular as I passed several groups of college students out for runs.

Rock Climbing

Given the sensitive status of the property, do everything you can to keep this place open for climbers.  From the Mountain Project link below:

Many of these walls could can be bouldered, however some of the higher faces (particularly the Main Wall on the south-western part of the island) could be dangerous to attempt without a rope. THERE IS NO FIXED PROTECTION ON THIS ISLAND, with only a few spots for some decent cam placements on the Main Wall. The tops of all of the cliffs can be accessed by walking around the footpath to the eastern side of the island and then scrambling up a few slabs to reach the upper plateau. This access to the top of the the walls could open up possibilities for top ropes, but I have yet to see people attempt it.

Mamacoke Island Climbing Map

A comment from 2018 notes that there was very tentative talk of bolting a few sport routes, but I saw no evidence of it in 2019.


See the interactive Mamacoke Island Geology Tour app


There are two archaeological sites on the island (and several more on Connecticut College property, see the report link below).  The first is the Mamacoke Cove site which is a shell midden heap, packed earth floor, and hearth/fire pit.  The area was discovered in 1975 by an undergraduate student and excavated in 1980 by

Yielding remains of shell, bone, stone tools and prehistoric ceramics, the site suggests inhabitants were present during the Middle to Late Woodland stage (ca. 1-1600 CE). A midden here was composed of much of the same deposit material as the Harrison’s Landing site but also included remains of deer, raccoon, beaver, rabbit, muskrat, porcupine, wild turkey, gray and red fox, gray squirrel, vole, mouse, chipmunk, otter, duck and turtle, as well as some bird and fish bones. A large Woodland village was probably located across the river on the current site of the U.S. Naval Submarine Base in Groton, and the Mamacoke site may have served as a seasonal shellfishing station (Juli, 1992).

The second is the Graves Rockshelter first discovered in 1927 by local children.

In 1980, local resident John Graves reported that as a boy in 1927 he found the remains of two human skeletons and a small collection of projectile points on the northern upland part of Mamacoke under a small rock overhang. Only one skull from the two skeletons remains, and it is apparently from an adolescent aboriginal female.

The site was named for Graves despite the 50 years it took him to donate the remains to a research center in Mystic.  Unfortunately, the discovery and disruption by the children and the ensuing 50 years removed any information that could be learned from the site.


The island has a long history of use by Native Americans.  At least one shell midden heap (a refuse pile accumulated from countless shellfish meals) was excavated in 1980.  Two Native American skeletons were discovered in a overhang shelter in 1927 though by children whose disturbance erased anything that could have been learned from the site.

The island was part of the Mamacock Farm from 1647 to 1940 as part of the Rogers family who grazed livestock on the marsh and rocky island.  The farm was split into three parts by John Rogers Jr after his death in 1753.  The northern gravel terrace served as a shipyard in the 1800s and at least three schooners were built there.  The railroad was built through the area from 1848-50.

The Bank of New London owned the island from 1940 to 1943 when it was purchased by the Merritt-Chapman & Scott Corporation a marine construction company.  They built two dolphins (I was confused at first, but dolphins are a set of pillar safety bumpers for mooring barges).  The company folded in 1954.

During World War II the Army installed gun emplacements on the east facing slopes of the Matthies and Avery Tracts.

The island was then purchased by Connecticut College on June 1st, 1955 for $15,000 (148k inflation adjusted in 2021) from the Merritt-Chapman & Scott Corp.  The Matthies Tract was purchased in and the Avery Tract was purchased in 1944 for $5,000.  Trails in the these parcels were developed by Mr. and Mrs. Joseph Porter for the college’s riding program from 1946-50.  Rt. 32 became too busy for the horses to cross by 1954 so the trails were left to be the walking trails that we enjoy today.

The area was designated an Important Bird Area in 2006.


The information shown here is for general reference purposes only. gives no warranty, expressed or implied, as to the accuracy or reliability of this data. Parking in all areas, whether designated here or not, is at your own risk. is not responsible for any damage or loss to vehicles or contents.
Last updated May 3rd, 2021


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