Adeline Jay Geo-Karis Illinois Beach State Park stretches about six and a half miles along Lake Michigan between Waukegan and the Wisconsin state line. Its 4,160 acres come in two disconnected halves, and the difference matters if you are driving out to swim. The north unit, 1,925 acres built around the former Camp Logan military site, is the eroding half. The south unit, 2,235 acres, holds the public swimming beach along with the park office, visitor center, campground, the Illinois Beach Resort and a 1,100 acre dedicated nature preserve at its far southern end. The beach people actually use sits at the north end of the south unit, a short walk east of the free lot off North Entrance Road.

Admission is free and the lot is neither metered nor gated. The Lake County visitor bureau lists park hours as daily from 8 a.m. until sundown, and the park office at 847-662-4811 is worth a call first, because IDNR warns that weather can close roads and facilities on short notice. Changing rooms, outdoor showers, drinking water, restrooms and picnic tables sit just behind the sand at the day use area, and a camp store and the resort are within walking distance.

No lifeguards work this shoreline. IDNR states that plainly on the park's own activities page, and it applies to both units, so everyone here swims at their own risk. Lake Michigan at this latitude stays cold well into the summer and does not really warm until late July or August. The water also turns over quickly when wind comes out of the north or east. Fishing is permitted along the beach but not inside the marked swimming areas.

Water quality is the thing to check the morning you go. The Illinois Department of Public Health tracks this beach in its BeachGuard system as Illinois Beach State Park South Beach, sampling from late May through the end of August. It is open as of this writing, but the record is uneven. Swim Guide puts the pass rate between 60 and 95 percent, and BeachGuard's history back to 2006 shows repeated short closures for high bacteria, usually one to seven days, most often with no pollution source identified. A separate stretch by the resort is monitored on its own and can be posted closed while the main beach stays open.

The erosion story belongs to the north unit rather than here. Sand once drifted down from southern Wisconsin, and harbor jetties and shore armoring up the coast cut off that supply while currents kept moving Illinois sand south. Losses in the north unit ran as high as 60 feet a year, worse after North Point Marina went in during 1989, and IDNR has periodically trucked dredged sand in from Waukegan Harbor and North Point to hold the line. A shoreline stabilization project completed in 2024 placed a row of offshore breakwaters, more than twenty by any count, plus over 750,000 tons of sand and 320,000 tons of stone along roughly two miles of shore. The beach grew back instead of vanishing.

Camping is in the south unit: 220 Class A Premium sites with electricity, showers and sanitary facilities, five of them accessible, open April 1 through November 15 and reservable through ExploreMoreIL up to 180 days ahead. Sites have no individual water or sewer hookups, but there are water points and a dump station, and summer weekends fill early. The south unit carries roughly five miles of trail including a 2.2 mile gravel loop, and the north unit has the 1.8 mile Camp Logan loop. Dogs are allowed on leash in picnic areas but not in the nature preserve, where fishing is also prohibited.