Phase 2 is the expert wave at Boise Whitewater Park on the Boise River, and it's not messing around — a steep, fast, green-faced wave built for advanced surfers who want real speed and punch. As one of the first adjustable river waves in the country, it helped prove a city-built feature could rival anything natural out there. Flows get dialed in through spring, summer, and fall, so the wave's character shifts through the season — come back a few times and it'll feel like a different ride. If Phase 2 is more than you bargained for, Phase 1 just upstream offers a friendlier version of the same stretch of river.