Jacques Cartier State Park is a 461-acre New York state park on the south shore of the St. Lawrence River in the Town of Morristown, St. Lawrence County, at the downstream end of the Thousand Islands region. It is run by the New York State Office of Parks, Recreation and Historic Preservation (OPRHP). The swimming beach sits at the back of a small sheltered bay on the western side of the park, between the riverfront campsites and the day-use lawns, with the city of Brockville, Ontario visible across the river.

The park entrance is on State Route 12, roughly 2.5 miles southwest of the village of Morristown along the Great Lakes Seaway Trail, and the ranger station is near the east end of the park road. Follow the park road down toward the water; there are parking lots beside the day-use area and playground a short walk from the sand. A bathhouse with restrooms and showers stands just behind the beach.

The beach itself is a short strip of sand facing a marked, guarded swim area in the cove. The bay is shallow and protected from the main river, so the water is calm and warms faster than the open river through July and August. The bottom is sand at the waterline, and the bay collects sediment over time, and OPRHP has planned a beach and day-use rehabilitation that includes dredging the beach and bay, adding new sand, replacing the lower shoreline retaining wall and rebuilding the bathhouse area. Swimming is allowed only during the posted guarded season. The guarded season usually opens in late June with hours of 10 am to 6 pm, seven days a week, and runs into August or early September, so call the park office at (315) 375-6371 before planning a late-summer swim.

Entry is not free. The park charges a vehicle entrance fee of $7 per day in both peak and off-peak periods, and New York's Empire Pass ($80) covers day-use entry. The park itself is open year-round from sunrise to sunset. Pets are allowed in the park on a leash no longer than six feet, but not on the guarded beach (service animals excepted).

Stay inside the swim area. Outside the cove the St. Lawrence carries a steady current, the water is much deeper, and the river carries Seaway ship traffic and heavy summer boat traffic. The park's boat launch is just east of the beach, so expect motorboats moving in and out of the bay. The beach can be closed on short notice after high bacteria counts or when lifeguards are not available, and the rehabilitation work may close parts of the day-use area while it is under way; OPRHP posts current beach water-quality results on the park's page.

The park's main draws beyond the beach are boating and fishing on the river, with launch sites and seasonal boat dockage. There is a campground with riverfront and wooded loops (about 89 tent and trailer sites with hot showers), open lawns for picnics, a playground, a rentable pavilion, and wooded trails that are used for hiking in summer and cross-country skiing and snowshoeing in winter.