Manali - Leh highway is a high-altitude road that connects Manali in Himachal Pradesh to Leh in Ladakh. It is one of the highest motorable roads in the world and passes through some of the most stunning landscapes of the Indian Himalayas. The highway crosses a total of six mountain passes before reaching Leh.

1. Rohtang Pass: The first mountain pass that comes on the way is Rohtang Pass, located at an elevation of 3,978 meters above sea level. It is one of the most challenging passes on the highway, with steep and narrow roads.

2. Baralacha La: The second mountain pass is Baralacha La, located at an altitude of 4,890 meters. It is the highest pass on the highway and offers stunning views of the surrounding mountains.

3. Lachulung La: The third mountain pass is Lachulung La, located at an altitude of 5,065 meters. It is also one of the highest passes on the highway and is known for its rugged terrain and unpredictable weather.

4. Nakee La: The fourth mountain pass is Nakee La, located at an altitude of 4,739 meters. It is a steep pass with hairpin bends and offers breathtaking views of the valleys below.

5. Taglang La: The fifth mountain pass is Taglang La, located at an altitude of 5,328 meters. It is the second-highest pass on the highway and offers panoramic views of the surrounding mountains.

6. Chang La: The sixth and the final mountain pass is Chang La, located at an altitude of 5,360 meters. It is the third-highest pass on the highway and is known for its steep ascent and descent.

In conclusion, Manali - Leh highway crosses a total of six mountain passes, namely Rohtang Pass, Baralacha La, Lachulung La, Nakee La, Taglang La, and Chang La. These mountain passes offer stunning views of the surrounding landscape and are a major attraction for adventure enthusiasts and tourists alike.