Unfortunately, I couldn't find any information or references to a Wilderness Rock River Canyon in the state of Indiana. It's possible that the specific location you mentioned may not exist or is not well-known. However, Indiana does have several other natural areas and attractions that might interest you. Some of these include:

1. Indiana Dunes National Park: Located along the southern shore of Lake Michigan, this national park offers stunning sand dunes, beautiful beaches, and diverse ecosystems. It's an excellent destination for hiking, bird-watching, camping, and swimming.

2. Brown County State Park: Known as the "Little Smokies of Indiana," Brown County State Park features picturesque rolling hills, dense forests, and scenic vistas. Visitors can enjoy various outdoor activities, including hiking, mountain biking, horseback riding, and fishing.

3. Turkey Run State Park: Situated along the banks of the Sugar Creek, Turkey Run State Park offers a unique landscape of sandstone gorges, rocky ravines, and forests. It's a popular spot for hiking through the scenic trails, camping, canoeing, and exploring the natural beauty of the area.

4. Indiana State Museum and Historic Sites: If you're interested in history and culture, the Indiana State Museum in downtown Indianapolis is worth a visit. Additionally, the state boasts numerous historic sites, including the George Rogers Clark National Historical Park and the Lincoln Boyhood National Memorial.

5. Indianapolis Motor Speedway: For racing enthusiasts, the Indianapolis Motor Speedway is a must-visit destination. Known worldwide for the Indy 500 race, the speedway offers tours, a museum, and opportunities to experience the thrill of motorsports.

When planning a visit to any of these locations, it's always advisable to verify specific details and current information from reliable sources such as official park websites, travel guides, or local tourist information centers. Additionally, the best time to visit Indiana's natural areas generally depends on personal preferences. Spring and fall are typically pleasant with mild temperatures, while summer offers outdoor recreational opportunities and vibrant greenery.