We finish off our last day of trekking with a very early start from Acacia.  The terrain is very dry and recently covered by ash from the 2008 Ol-doinyo Lengai eruption.  We maximize our trek in the early hours of the day to avoid the late morning sun intensity and heat.  We descend the Rift Valley Escarpment, via Pembe ya Swala to the base of Ol Doinyo Lengai.  At the base we are picked up by our vehicles and transferred to our camp in Lake Natron for Lunch.  Late afternoon excursion to Lake Natron shores to view the Lesser Flamingos in their breeding habitat or for the fitter ones a hike up to the Engare Sero waterfalls.