A nice little park (it's 5 acres on paper, but most of it is forest or ravine) tucked back in a…read moreresidential area, Port Clinton Park is walking distance from downtown Highwood and the old fort. Since it's kind of hidden, and there are only two or three dedicated parking spots, it is mostly only known by the local neighbors.
A good chunk of it is wooded, with a small baseball/softball diamond at the northeast corner off of Bloom St., and a playground off the St. John's entrance. There's an okay-ish basketball court adjacent to the playground, that sometimes doesn't have a net on the hoop. Last I checked, they put one picnic table back, though they might have another there soon. The playground equipment is great quality, everything is well maintained, and the park district does a good job tending to the landscaping. The only lights are from neighboring houses, so head out before dusk. I also recommend you use quality mosquito repellent, because - despite the best efforts of the park district - the mosquitos can be kind of awful in the late summer just because of its forested nature.
The small parking area along St. John's is gravel, and can only accommodate two or three vehicles - just be careful not to block off the neighbors' driveway north of the parking spots. You can also park along Bloom St., and walk through the path to the playground, but it's a narrow-ish section, so pull as far to the side as possible. Also, interestingly, I have seen whitetail deer chilling out at the park, so maybe to be a little careful - they'll mess ya up if you startle them. Maybe also watch your kids around the edges, as some of the wooded area is just thick enough that younger kids can be hard to find when playing hide-and-seek. Ravines run through it, so also make sure younger kids don't accidentally stumble down. They're not really dangerous, but dirty, and could be a little hard to climb out of without getting muddy.