Visitors to Sielbeck Forest pass through bottomland hardwood forest and a forested swamp mirroring the wilderness documented by public land surveyors in 1807. This island of somber, gray timber once was part of the Big Black Slough, a wetland-rich floodplain that once covered thousands of acres in Massac, Pope and Johnson counties in southern Illinois.

Today, nearly all of this part of the Ohio River floodplain has been drained, cleared and tiled to feed a world hungry for corn, wheat and soybeans. Despite the insatiable appetite of plow, ax and saw, this tract of land remains largely undisturbed.

Activities

Fishing
Fishing is allowed on the two small ponds, with largemouth bass and bluegill the predominant species.

Hiking (but no trails)
While hiking around the area one can see some of the enormous trees protected by the Sielbeck family and state. No trails, day use area, or major improvements exist or are planned as a means of keeping the area natural as possible. After the reforestation project is completed converting all row-crop fields back into trees, fields and wood lots will be allowed to revert back to their natural state.

Hunting
Hunting species such as deer, squirrel, dove, rabbit, quail, waterfowl and turkey is allowed on the area. Statewide hunting regulations apply. No night hunting of any type is allowed.species such as deer, squirrel, dove, rabbit, quail, waterfowl and turkey is allowed on the area. Statewide hunting regulations apply. No night hunting of any type is allowed.

Two hunter sign-in boxes are available at the southernmost entrance parking lot and on the northwest corner parking lot on Upper Salem Road. Deer hunters can obtain a deer hunter's packet, which allows hunting on both Mermet Lake State Fish and Wildlife Area and Sielbeck Forest State Natural Area without signing in each time they hunt.