Among the various picnic areas in the park the day use area located on the northwest side of the lake has the swimming facilities, and is also out of the shade of the trees so that on a clear day you can enjoy the sunlight.
Some of the picnic tables have cooking stands near them.
The restroom facilities also have showers in the restrooms. The good news is that you can shower after swimming in the lake. The bad news is that it costs $0.50 for 3 minutes of shower. If you happen to go into one of the rooms after someone has showered there may be a mess, as the shower is located in the corner of the restroom stall and the possibility of them splashing water everywhere, including onto the entire floor and all over the toilet, may be fairly high. Some of the showers are equipped with a fold-down bench to allow those who need or want to sit during their shower to do so.
The swimming area is marked off with a floating rope.
The area also has a playground and play structure near the restroom building.
There are a number of picnic areas in the park, including picnic shelters. Some of these shelters and areas are reservable for groups. Most of them are close to the shore of the lake. All of them appear to be wonderful, but I would also expect all of them to be heavily used during the peak tourist season.
These several areas include a number of picnic tables that are scattered around by the day use and swimming area (turn left just after entering the park and cross the bridge over the lake). These areas tend to not have any shelter, from either trees or a shelter structure. The group shelter areas that are reservable are located near the campgrounds (go straight after being presented with an intersection where you can also turn left and cross a bridge over the lake).
From the signs in some of the areas along the park trails, it is obvious that the trails connecting to those in the park actually continue well outside the boundaries of the park.
Just how far these go will have to be explored on further visits.
The name of the forest in which the park sits is the Chapin Collins Memorial Forest, and that deserves a bit more research to determine what lies outside the boundaries of the state park.
Forest wild flowers may be viewed here. Depending on the weather of the particular year, late April is pretty good for many flowers, including Skunk Cabbage, Trillium, and many others.
It is also possible to see remains of the huge trees that once lived in this forest. Along the trail that wanders along the south side of Lake Sylvia it is possible to get very close to a number of these old stumps. Most of them have deep marks in them where spring boards for those cutting them down once had to stand because they could not cut any lower on the trunk due to the steep hillsides or the tough root knot.
Please DO NOT pick the trillium. They are very sensitive plants in the northwest climate, and it has taken quite a long time for them to recover in places.