Thunder Rapids is a waterfall on outlet of Thunder Lake in Sweet Grass County, Montana, in the Middle Rockies region, with a total height of about 480 feet. It lies about 20.9 miles northwest of Big Timber and roughly 87.5 miles west of Billings as the crow flies.
At 480 feet it stands in the tallest quarter of Montana’s 123 waterfalls with a recorded height, ranking 30th; the typical Montana waterfall is about 250 feet.
The Middle Rockies are high, glaciated mountain ranges with alpine peaks, subalpine fir and spruce forest, lodgepole pine and grassy intermontane valleys. Snowmelt streams cascade down glacial valleys and canyon walls.
There are 6 recorded waterfalls in Sweet Grass County. Halfmoon Falls, a 140-foot cascade waterfall, is about 1.7 miles away.
Thunder Rapids is located at 46.0341° N, 110.2839° W. The listing is based on the World Waterfall Database, one of the sources compiled by the U.S. Geological Survey in its inventory of waterfalls and rapids of the conterminous United States. The exact position has not yet been verified on aerial imagery, so treat the map pin as approximate. Details on trails, parking and access have not been documented for this waterfall yet.