From Appelton Pass follow the trail down to Sol Duc creek. After 4 km turn east as you reach the creek towards Sol Duc Ranger Station. Cross the creek and follow the trail climbing up to Heart lake, which is a great spot for a short dip.
From Heart Lake climb of further until you reach the turn off to Cat basin. Follow the cat basin trail for about 2km to the second turn off to (first turn off leads to a campsite). Turn left on this smaller trail that leads up towards the High Divide ridge. For the next 5km the trail runs along the south side of ridge. You have to cross several boulder fields and sometimes the trail is hard to follow. After this 5 km, the trail crosses the ridge and from now on you can see Appelton pass. Follow the trail for another 5 km on the north side of the ridge to back to Appelton pass.
The loop took us about 9 hours to complete including a longer break at Hear lake. It offers fantastic views of many peaks in the park and above all the last 10 km along the ridge are just fantastic.