Today is considered to be the hardest day of the trek, starting early from Soraypampa the first few hours of the day are quite easy going with the trail gently making their way up the valley leading to Salkantay. As you continue up the valley from Soraypampa the trail becomes more and more barren as the vegetation and the birdlife are unable to contend with the altitude, however the views of Humantay and Salkantay looming above you easily make up for this.
It's about a one and a half hour walk to Salkantaypampa after which the trail begins to ascend more steeply as it climbs towards the base of Salkantay. There is one particularly tough ascent about an hour before the pass called the seven snakes, a switchback which goes straight up the mountainside for about 400 vertical meters / 1310ft. Once you've made it up the switchback the trail levels out again until you reach the small lake at Soyrococha where it's common to stop for a break before the final climb up to the pass. From here it's just another 40 a minutes up to the pass after which it's all downhill until you reach Machu Picchu.
On this side of the pass the environment changes considerably, the wildlife becomes more abundant and you may spot deer and a small rabbit like chinchilla called Viscacha. There is also a wide variety of birdlife to be seen including Ibis, Lapwings and Andean Geese and gulls.
There are various campsites you can use today, Wayracmachay is the first which is about three hours after the pass; the other campsites are Chaullay or Collpapampa which are found on opposite sides of the river to each other, both are about a four hour trek from Wayracmachay.