Most barrier islands and summer destinations have been loved to death. The Hamptons, the Jersey Shore, Cape Cod — all offer genuine pleasures, but the footprint of development is everywhere, and the idea of encountering actual wilderness requires a certain willful imagination. Mashomack Preserve on Shelter Island is an exception. It is 2,350 acres of land that will never be developed, never be subdivided, never have a resort built on it. It covers one-third of the entire island. It is the reason Shelter Island looks the way it does — and it is one of the genuinely underappreciated natural treasures on the East Coast.
What the Preserve Is and How It Came to Be
Mashomack is owned and managed by The Nature Conservancy, which purchased the land specifically to prevent the development pressure that had already transformed so much of Long Island's East End. The transaction was deliberate: a decision made in the 1980s that this particular piece of land — its mix of tidal creeks, old-growth tupelo and oak forest, coastal grasslands, and 11 miles of pristine shoreline — was worth protecting permanently. The Conservancy's investment has compounded over the decades. What exists now is a functioning, largely intact coastal ecosystem in a region where such things are genuinely rare.
The preserve is often described as "the jewel of the Peconic Bay" — a phrase that sounds promotional until you actually spend a morning on the Blue Trail and understand what it refers to. The quality of the habitat, the density of wildlife, and the sheer visual scope of the coastline along the preserve's southeastern edge are genuinely extraordinary by any standard, not just by local comparison.
The Four Trails
Mashomack has four color-coded trails that fan out from the main entrance on the island's south side. They are designed to accommodate different levels of commitment and physical ability, and each offers a genuinely different experience of the preserve.
Red Trail — 1.5 Miles
The Red Trail is the right introduction for a first visit or for anyone who wants a meaningful walk without committing most of a day. Easy terrain, well-marked, with coastal views that open up about halfway through the loop. It takes an hour to ninety minutes at a relaxed pace. Ideal for an early morning before the heat builds in July, or for families with young children who need a real payoff without excessive mileage.
Yellow Trail — 3 Miles
The Yellow Trail adds tidal creek crossings — narrow wooden footbridges over the creeks that cut through the preserve's interior — and better birding opportunities than the Red. Three miles, moderate difficulty, roughly two hours. The creek sections in spring and early summer are where you're most likely to encounter diamondback terrapins, the salt-tolerant turtle species that breed in the preserve's tidal areas. The Yellow Trail is the best single option for visitors who want a real hike without the full-day commitment of the longer routes.
Green Trail — 6 Miles
At six miles, the Green Trail takes you deep enough into the preserve that the sounds of the island — the distant ferry horn, the occasional car — disappear entirely. Three to four hours of moderate hiking through oak and tupelo forest, past tidal creeks and freshwater ponds, with long sections where you are unlikely to encounter another person. The solitude on the Green Trail on a weekday in late June, before the full summer crowd arrives, is the kind of thing people describe when they try to explain why they keep coming back to Shelter Island.
Blue Trail — 10 Miles
The Blue Trail is a full day. Ten miles, five to seven hours depending on pace and how often you stop. It follows the preserve's southeastern coastline for a significant stretch — those 11 miles of undeveloped shoreline that the Nature Conservancy protected — and the views are what photographers come for. The trail opens onto broad coastal panoramas with no buildings, no infrastructure, nothing to interrupt the sight line between you and the water. Bring enough food and water, wear shoes appropriate for uneven terrain and possibly wet creek crossings, and start early enough to avoid hiking the final miles in afternoon heat. This is the trail that changes people's understanding of what the East End can look like.
Wildlife: What You'll Actually See
Nearly 200 bird species have been documented in Mashomack, and the preserve is considered one of Long Island's premier birding sites. The variety is driven by habitat diversity — the mix of forest interior, tidal marsh, coastal grassland, and open water creates conditions that attract species across a wide range of ecological niches.
Ospreys are the most visible large raptors; their nests are visible from multiple points on the trails, and watching an osprey hunt over the tidal creeks is one of those experiences that doesn't get routine no matter how many times you see it. Great blue herons are common along any water feature. During spring and fall migration — May through June, September through October — the variety expands dramatically, and birders willing to move slowly along the Yellow Trail at dawn can have exceptional mornings.
The piping plover and least tern, both federally threatened species, nest on the preserve's beaches. The Nature Conservancy manages their nesting areas carefully, and visitors should respect any posted closures during nesting season (May through July). Diamondback terrapins — the only turtle species in North America adapted to brackish water — are reliably seen near tidal creeks. White-tailed deer are so common on Shelter Island that they have become a management challenge; you will almost certainly see them. Red foxes are present and occasionally visible in early morning.
Kayaking the Preserve
The tidal creeks and protected coves within and adjacent to Mashomack are among the best kayaking environments on the East End. The water is calm, the currents are mild, and the paddling takes you into habitats that are inaccessible on foot — deep into the marsh grasses, past the diamondback terrapin habitat, with views back toward the forest that are genuinely unlike anything you can see from the trails. Several launch points exist near the preserve. If you're staying at Glynn Gardens and considering a kayak rental for the week, the Mashomack shoreline should be the first destination on your list.
Hours, Access, and Practical Information
Mashomack Preserve is open 9am to 5pm from March through September, and 9am to 4pm from October through February. It is closed on Tuesdays throughout most of the year, but is open daily during July and August. The entrance is on the south side of the island — a short drive from most Shelter Island properties, including Glynn Gardens.
The practical preparation matters more here than on most day hikes. Ticks are a genuine concern; Shelter Island's deer population sustains a significant tick population, and a full tick check after any trail should be treated as non-negotiable rather than optional. Wear light-colored clothing so ticks are visible, tuck pants into socks on the longer trails, and check thoroughly when you return. Bug spray with DEET is effective against both ticks and mosquitoes in the marshy sections. Bring more water than you think you need; there are no facilities on the trails. Waterproof shoes or trail shoes with decent grip are worthwhile for any trail involving creek crossings.
For photography, the Blue Trail's coastal section at golden hour — roughly an hour before sunset in July — produces the kind of light that makes images look edited when they aren't. A telephoto lens is worth carrying for bird photography; 300mm or longer will get you usable osprey and heron shots without disturbing nesting activity.