The loop as mapped begins from one of the major trailheads, and if you head in a clockwise direction, it begins by almost immediately passing Upper McKinney Falls—the largest of the two waterfalls. It's a true delight that even from this smooth paved path, you can enjoy a view of this gorgeous waterfall and the overhanging limestone cliffs that form a small amphitheater above Onion Creek.

Once done at the falls, the Onion Creek Trail takes a loop around the outside of the campground ring, twisting and turning beneath the overhanging branches of towering trees. Take some time to appreciate the diversity of the forest. Here in the park, you can see "bald Cypress, sycamores and pecan trees along the banks of Onion Creek and live oak, ashe juniper, and mesquite. . .on the drier uplands," according to Wikipedia.