It takes a lot of time and effort to visit the most remote and, to me, the most interesting, part of St Kilda: Gleann Mor. A visit to the glen can take four to five hours, which allows for spending a couple of hours in the glen to visit all its amazing ruins and make the descent to Tunnel Cave. Day trips to Kilda just barely allow time to make this long trek, so the best way to see Gleann Mor without having to hurry is to visit the island on a cruise that allows at least a full day ashore.
The typical route to the glen first involves climbing 800 feet to the saddle below Mullach Sgar. From there you can descend directly into the glen. But since you've gone to the effort of climbing so high, before descending into Gleann Mor I'd suggest strolling to the northwest along the ridge to Mullach Bi and pay a visit to the Lover's Stone.
|Gleann Mor seen from near Mullach Bi|
|Descending into Gleann Mor|
|Bonxie on the attack|
|Flying-boat remains in Gleann Mor|
The ancient ruins in Gleann Mor are astounding. Over a dozen sets of beehive cells, some linked together with odd, horn-shaped forecourts. No one knows for certain how old these things are, but some may date back as far as the 4th century. The most complex cluster is what's known as the Amazon's House (see this CANMORE page for more).
|Clusters of ruins in Gleann Mor|
|Soay sheep mowing the lawn of Glenn Mor|
No visit to Gleann Mor is complete without making the descent to Tunnel Cave. At the tip of the cliff on the east shore of the bay you will find a natural ledge that leads down to the sea, and the entrance to the cave. (You can see the sloping ledge in the next photo.) The last bit of the descent can be slippy, so be careful. Once in the cave you can walk to its far end where there is a great view over to Boreray.
|The sloping ledge down to Tunnel Cave|
|Boreray seen from the tunnel|
From the tunnel you have your work cut out for you to return to Village Bay. The saddle below Mullach Sgar is a mile to the south (and 800 feet up). Alternately you can climb directly SE up the ridge to Mullach Mor, and then on to the top of Conachair. That route is only three-quarters of a mile as the gannet flies, but has 1234 feet of elevation gain. Either way can be tough going through thick grass and attacking bonxies. The climb up Conachair is one you'll remember for a long time; especially the view from the top down to Village Bay on one side, and Boreray on the other.
If you do make the effort to walk to Gleann Mor, chances are you'll have it mostly to yourself. My last visit there was in 2015. Five day-boats and three cruise ships were in village bay. A hundred visitors were ashore, but when I was in Gleann Mor I only saw one other person.