Sleeping Beauty is a standing wave on the racecourse section of the Rio Grande in Taos, New Mexico. It’s an early season wave, especially by Colorado standards. The New Mexico season tends to start quite a bit earlier and run warmer than Colorado rivers. Its character changes from a breaking green wave on one side and a hole on another at 500 cfs or so, to a big wide wave over 750 cfs, and big and fun over 1,000 cfs.
The wave has nice eddy access and the runout is pretty safe, even at high water, making it a relatively friendly place to surf. At higher water though (>1500), swims get tougher and your board can get pulled into a small pourover/hydraulic where it may find some dings.
The Rio Grande gauge nearby gives an accurate read on the flow. Look for >500 to start and >1,000 to drive for it. For the most part, the more water, the better.
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The wave is just off Highway 68 in the racecourse section of the Rio Grande, between the Big Rocks and Sousse rapids.
Thanks to Brian Levine for the info.