Westcott Beach State Park is a 318-acre New York State park on Henderson Bay, the sheltered southeastern corner of Lake Ontario, run by the New York State Office of Parks, Recreation and Historic Preservation. The land once belonged to the Westcott family and was sold to the state in the late 1940s; the park opened to the public around 1950. The guarded swimming beach is a strip of sand at the foot of the park's lower day-use area, facing west across the bay toward the open lake, with a stone breakwater and a small marina just to the north.

The entrance is on NY Route 3 in the Town of Henderson, about 3 miles southwest of the village of Sackets Harbor and roughly 25 minutes from Watertown. Route 3 splits the park in two: the wooded upper section holds the Plateau campground, cottages and trails, while the beach, picnic grounds, playground, boat launch and the main campground sit on the lake side. Pay at the contact station just inside the gate, then follow the park road down to the large lots behind the beach. A first aid station stands at the edge of the sand.

The beach shelves gradually into the bay over sand mixed with some pebbles and stone, so check footing as you wade out. Henderson Bay is shallower and more protected than the open lake, which helps it warm up by midsummer, but Lake Ontario is still cold early in the season and a west wind can push surprisingly steep waves onto this shore. Swimming is allowed only when lifeguards are on duty. The state's swimming season runs from late June to early September, with main beach swimming hours of 11am to 7pm in recent seasons, and it warns that those hours can shrink when lifeguards are short. Pets are not allowed on the guarded beach.

Entry is not free. State Parks charges a Beach and Vehicle Entry Fee of $8 per vehicle for peak-season day use, with buses at $35 a day, collected from the first weekend in May until Columbus Day. The park itself is open sunrise to sunset all year and no entry fee is listed outside that window, but with no lifeguards on duty there is no swimming then. The $80 Empire Pass covers vehicle entry here and at most other state parks for the season. Campsites run $18 to $31 a night, with $5 more for non-New York residents.

The main hazards are the lake itself: wind-driven waves, cold water early in summer, and the chance of a temporary swim closure after heavy rain or a high bacteria reading, which New York State Parks posts on the park's water quality page. Broken mussel shells can be sharp underfoot, so water shoes help. The boat launch and marina channel are next to the swim area, so stay inside the marked zone. Call the park at (315) 938-5083 before a long drive if the weather has been rough.

Beyond the beach, the park has picnic tables and rentable pavilions, a playground, basketball and volleyball courts, about 168 campsites spread between the lakeside loops and the Plateau loop, and a row of modern rental cottages on the bluff with views across the bay. Four short color-blazed trails (Blue, Orange, Red and Yellow, from 0.3 to 1.3 miles) climb through woods and meadows on the upper side of Route 3 and are used for cross-country skiing and snowshoeing in winter. The boat launch is open year round from dawn to dusk, and paddlers can put in there to explore the bay shoreline.