Visit the Mendenhall glacier and then cross over to the glacier itself. If the lake is frozen it's a 1.5 mile walk (or bike ride) to get the face. Otherwise, it's 3.5 mile hike from West glacier trailhead. Ice caves constantly change so finding one during daylight is the best bet.
Ice caves are quite unstable. Don't attempt to do a shoot inside one without help from someone that understands them. Also wear proper safety gear. For the star trails, I sat outside the cave for the majority of the shoot just to be on the safe side.
2 hours of star movement stacked to create the star trails from inside an ice cave under a glacier. I used a flare to light up the glacier ice in the dark to create a fiery look that stands in stark contrast to the standard blue look.