G-Spot is about as low-commitment as river surfing gets — a natural wave on the Yellowstone River just outside Columbus, Montana, reached by parking along the frontage road near mile marker 5 and walking a short trail across the railroad tracks. The wave actually changes shape with flow: a soft lower wave fills in around 6,000 cfs, a gentler middle wave shows up near 7,400, and a finicky, shoulder-high peak locals call the Mac G appears around 12,000, with the sweet spot usually 9,500 to 10,400 cfs. It's easy to paddle onto and eddy back from, which is exactly why it's become a reliable beginner spot. Just mind your footing on the rocky approach, since low water makes for a boney ride.