First to Balchalpsee is a 4-mile out-and-back trail. I did it on a rainy overcast day and the views were still spectacular. At a moderate pace, it took only 1 hour to complete the out-and-back hiking portion, with 20 minutes spent at the lake overlooking the glaciers.
There is a fee to ride the lift up to the top of First where you'll begin the hike. For more information on pricing and operating hours, visit jungfrau.ch.