The first day of the Camino del Norte is the hardest of the whole walk. We did the Norte in 2018 and skipped the first stage. This year we wanted to try it out, seeing that we were six years older. To make it even possible we did two things. We took a taxi up to the Guadalupe Sanctuario which saved four miles and 600 feet of elevation climb. We also decided to stop before San Sebastián which saved four miles. Still it was very hard, harder than we expected.
There are two routes from the Sanctuario: the official route, which is mostly flat except for a descent of 600 feet at the end, and is pretty routine. The second is the Purgatorio route which goes to the top of Mount Jaizkibel.
Right after the two routes split we climbed a ridiculously steep trail. Here is a photo.

After that it goes up and up and on and on. Quite rocky. But the route has spectacular views. Some photos.

Once you pass the mountain top and its towers, you start down. This is steep and rocky and slow going. Finally it merges with the lower trail and it is pretty easy into Pasajes.
Numerous times on the trail we wished we had taken the lower route but when we were back in Pasajes, after checking in and having a lovely meal we decided it was worth it.