Directions From IF on Hi 20
Go past "Henry's Fork Landing at Mack's Inn"
Left turn onto National Forest Road 053 RD (a.k.a. Red Rock Rd) at (44.57655987335274, -111.33710145950317)
Go around Henry's fork lake, past Red Rock RV & Camping Park, turn left at junction near (44.617973979966706, -111.45299434661865) onto Red Rock Pass Road
stay to the right at this intersection (44.61320075434697, -111.63276672363281) . Don't worry if you miss it, there is another right coming up but you will need to loop around more.
Assuming you didn't miss it; you will go around 2 small ponds (first Widgeon Pond and then McDonald Pond )
Stay to the right and you will go to Elk Lake.
It is pretty much a one way dirt road now. You will pass Elk lake and dead end into Hidden lake near the coordinates (44.713699189815564, -111.60654544830322)