The essential Henry Coe Hike: 10 arduous miles through the park's demanding mountainous terrain. China Hole is one of the most popular destinations at Henry Coe State Park. Spring rains create a picturesque swimming hole at the confluence of two creeks, making the nearby backcountry campsite a prized locale for overnight outings. A day hike to China Hole is a perfect alternative if you hate to sleep on the ground but love to get your heart pumping under the California sun. You'll also descend along the Madrone Soda Springs Trail and the Mile Trail, which passes the decaying remains of an era when the springs were a major tourist attraction. Best time to go: spring, when the hills are green and the wildflowers are popping, and early summer, when it's warm enough to swim at China Hole. The water gets more dank as summer progresses -- the puddles remaining after July tend to reek.