Lost Horse Lake is a 14 mile out and back trail located near Hamilton, Montana and is rated as moderate. The trail is primarily used for hiking and is accessible from July until September.
I took my family in late summer of 2014. Great hike. You need to pay attention because the trail is not well travelled after Fish Lake. I would not do it without a GPS. It is somewhat difficult to get to Hackney Lake, and more difficult to get back to Lost Horse Lake. We did catch some of the best tasting fish I've ever eaten at lost horse. It is on our list to hike again!