Thousand Springs Trail and Castle Lake is a 9.6 mile lightly trafficked out and back trail located near Rexburg, ID that features a river and is rated as moderate. The trail is primarily used for hiking and is accessible from July until August.
Drive from Idaho Falls on US26, at about 14 miles turn north following signs to Kelly Canyon Ski Area, Pass the ski resort and continue on the dirt road. When you get to the parking lot (there is a map of the area - go look at it), follow the forrest road 218 (going up). Stay on this road for about 12 miles, then turn right on an unmarked road that will take you to the trailhead.
This is an ok hike and a good hike for those in the Rexburg area. The hike is fully in trees and is a multi-use trail. I was the only hiker but ran into a couple of motor bikes and a couple of four wheelers. Only wildlife I saw were cows and there were some flies but they didn't mess with me. Castle Lake is a bit of a disappointment as it is more of a small pond with a lot of grass in it. Overall, hike was easy only climbing just over 1,000 feet. You have to travel a ways on dirt forest service roads to get to the trail head. The 10 mile hike out and around Castle Lake was just ok but worth a few hours on a Saturday morning to get out in nature if you don't want to go a long way from home.
Wouldn't recommend this trail. The scenery is just average and the reward isn't great enough for the amount of work it takes. It's not a hard hike but it's certainly not easy. It just didn't seem worth it to me not to mention we were being bitten by horse flies the entire way there and back. There's prettier hikes to do than this one.
Good hike! Well marked trail! Definitely not a easy hike. I would say more moderate. Watch for ATVs on the trail!
First part of the trail is actually an ATV trail, but after 2 miles it turns right and gets a lot better with pretty views. Early June and there was quite a bit of snow.