From there it is a pleasant walk then skin up through the trees, then open pastures above, before steady slopes take you up to the Simelipass at 3022m. It is a relatively short descent the far side, aiming to clear the head of the gorge, near Obers Fulmoos at 2440m. A further easy, short skin up to the Sirwoltusattel takes you to 2620m. It is a good 800m descent down to Niederalp. Make sure you clear the large cliff band that is hidden from above, by traversing sufficiently far E, before your N facing descent.
There are likely to be plenty of tracks from day tourers having been up the Schilthorn, a popular nearby peak. From Niederalp you can miss out a bit of road by skinning up to the W, before crossing to the Simplon Hospice. This is a fantastic and welcoming place, an imposing building, ideally placed at 2000m, with a real sense of history. When we were there the Swiss army were using the car park for their passing out parade and celebrations for the local cadets!