Fall Colors · Wildlife
Most of the trail is a gravel surgace. It really isn't that bad, but be prepared to stop and empty your shoes at least once. The trail is a nice and wide doubletrack (if you like singletrack, you'll hate this trail). It is busy but not to the point of being a traffic jam like some trails in the park can be.
I've used this trail several times as my long run (>16 miles) in preparing for road marathons when I get tired of running on roads and just need a break from the concrete.
This hidden gem gets overlooked by many park visitors because it is a bit longer (at just over 8 miles one way) and there just isn't a good way to loop it. That aside, it has some great hills as well as some wonderful flats to rest the quads.
It works out perfect starting in Cave City and running up to the Mammoth Cave National Park Visitor Center where you can refill a water bottle, catch your breath from all that uphill, and then turn and run back to your car. Or you can be lazy and hitch a ride back to Cave City with one of the many park visitors. (Although, I wouldn't condone hitchhiking in this day and age). This is also a logical place to have a friend come pick you up.
Flora & Fauna
Early in the mornings you'll see deer and wild turkey literally EVERYWHERE you look.