The geography of Thimphu is defined by its central river valley.
* **Wang Chhu (Thimphu River):** The lifeblood of the valley, this fast-flowing, clear mountain river runs directly through the center of Thimphu. It provides water for agricultural irrigation, supports local hydroelectric projects downstream, and offers a scenic backdrop for the city, particularly as it flows past Tashichho Dzong. * **Mountain Streams (Chhus):** Numerous small tributaries and cascading streams flow down from the surrounding Himalayan peaks to join the Wang Chhu, often lined with prayer flags and small water-driven prayer wheels.