Sky Creek produces two small but pretty waterfalls where it passes underneath the Thornton Creek Road for the second time as it climbs to the Thornton Lakes Trailhead. The upper of the two falls skips 29 feet down a blocky cascading-style fall before cascading further through a rock and log choked streambed. Sky Creek is not a large stream by any means and though it drains from high up the side of the mountain where winter snow will linger through the spring and into the early summer months, the volume of water in the creek will be reduced significantly by August and will usually just be a trickle by September.
- Upper Swayel Falls is the Unofficial name of this waterfall.
Swayel is a Nooksack Indian word meaning "sky", "sky-born" or "of the sky". While the Nooksack tribes didn't really occupy this part of the state, the dialect spoken by the Skagit tribes was a similar Lushootseed dialect but the word they used for similar meanings is essentially unpronounceable using the english language. The name comes from Burlington-based waterfall hunter and frequent collaborator Aaron Young.
Upper Swayel Falls is found near the Thornton Lakes Trailhead in Ross Lake National Recreation Area. Take Highway 20 3 1/4 miles west from the Newhalem General Store to the Thornton Creek Road (signed for Thornton Lakes) and follow it up the mountain for 4.2 miles to the second crossing of Sky Creek (neither crossing is terribly obvious) and park at a turnout just past the creek. The falls lie just downstream of the road - the best route down is about 100 feet to the west of the creek, where the forest is free from underbrush.