12. 1st peak of the Crown of Siam from the southwest, route 26 c/d, fig. 5.

The ascent can be made either from the base camp or from a bivouac on the left moraine of the White Pyramid's Eastern glacier.

From the Four Pass, descend along a gentle snowfield to the right, under the cliffs of the western slopes of the southern ridge of the 1st peak of the Crown of Siam. Traverse the snowfield to reach broad ledges covered with fine scree and running parallel to the rocky ridge. Move along these ledges until they intersect with a shallow, snow-filled couloir. The latter is 1.5–2 m wide.

Further movement:

• up to the right along the couloir, where after 12 m, convenient ledges begin, leading up to the ridge. This section is well-defined, as it is bounded on the left by difficult rocks.
• before reaching the ridge, turn left under a rock wall 10–12 m high, with outcrops of black rocks in its upper part.
• under this wall, pass to a gap in the ridge.

From the gap, ascend rocks with good holds to a small platform at the level of the upper edge of the wall. Belay is piton. Above the wall, a narrow ledge goes left, allowing traverse of the rocks above the wall to a convenient exit up to a broad, gentle platform. Ascend a short, wide couloir leading to the pre-summit ridge, up to the right onto the ridge. Along the ridge to the summit is 200–250 m.

In some sections of the ridge, alternating belays are required. Descent from the summit is by the ascent route. The ascent takes 7 hours.

Fig. 5.