New York State Parks · New York
Mary Island State Park
New York State Parks · New York, United States
- Sites
- 12
- Hookups
- 12 no hookups
- Drinking water
- Yes
- Restrooms
- Yes
- Showers
- Yes
- Pets
- Yes
- Elevation
- 243 ft
- Dark sky
- Bortle class 3
- Cell coverage
- Verizon weak · T-Mobile none · AT&T none (carriers' 4G LTE filings to the FCC, 2025-12; not measured here)
- Lake
- St. Lawrence River
- Nearest town
- Clayton
- Phone
- (315) 482-9381
- Activities
- Camping
About
Mary Island State Park offers 12 waterfront, boat-access-only campsites on the St. Lawrence River east of Wellesley Island, with Canadian shoreline views. A boat of at least 14 feet with a motor is required to reach the island; rentals are available at nearby marinas. Hot showers and restrooms are available, and boats may be beached or moored near sites. Pets are permitted, maximum two per site, with proof of current rabies vaccination and a 6-foot leash.
Fees
Primitive boat-access sites are about $14/night base plus a $7.25 reservation fee; a waterfront surcharge likely applies. Out-of-state campers pay an additional $5/night. Confirm exact rates when booking.
Weather, month by month
| Month | Typical high | Typical low | Coldest night | Hottest day | Years with a night below 32°F |
|---|---|---|---|---|---|
| January | 27° | 15° | -13° | 41° | 11 of 11 |
| February | 30° | 14° | -18° | 50° | 11 of 11 |
| March | 40° | 26° | 4° | 59° | 11 of 11 |
| April | 53° | 35° | 23° | 79° | 8 of 11 |
| May | 67° | 47° | 33° | 83° | 0 of 11 |
| June | 73° | 56° | 46° | 87° | 0 of 11 |
| July | 81° | 65° | 56° | 96° | 0 of 11 |
| August | 78° | 65° | 57° | 88° | 0 of 11 |
| September | 73° | 58° | 48° | 83° | 0 of 11 |
| October | 57° | 46° | 33° | 76° | 0 of 10 |
| November | 42° | 32° | 16° | 62° | 9 of 10 |
| December | 35° | 25° | 8° | 58° | 10 of 10 |
Mid-month figures from 2016–2026 of daily weather at this spot (ERA5 reanalysis via Open-Meteo, CC BY 4.0), in °F. Typical is the median; coldest and hottest are the extremes seen.
Nearby campgrounds
- Keewaydin State Park · New York State Parks · 3 mi · 47 sites
- Kring Point State Park · New York State Parks · 3 mi · 95 sites
- Grenadier Central · Parks Canada · 3 mi · 16 sites
- Dewolf Point State Park · New York State Parks · 4 mi · 14 sites
- Grenadier East · Parks Canada · 6 mi · 3 sites
All public campgrounds in New York · Every state and province · Facts read from the operator 2026-08-25. Confirm fees, rules and current status with the operator before you go.