Lake Natron is a mineral-rich soda lake in northern Tanzania, at the border with Kenya. It’s a breeding ground for hundreds of thousands of lesser flamingos, despite the highly alkaline state of the striking red waters. It sits below Ol Doinyo Lengai, a soaring active volcano in the Rift Valley. Trails lead from the lake to the Engero Sero waterfalls, which flow over craggy rocks into a natural pool.