The drive down from Gangtok is dominated by Teesta river, which seems omnipresent through much of the journey. The National Highway 10 (previously, NH-31A) snakes along the mountain curves and runs almost parallel to the Teesta river. There are good stretches passing through refreshingly green forest areas and meandering Teesta river keeping company all along.
The Teesta River is a 309 km long river flowing through the Indian states of West Bengal and Sikkim through Bangladesh before emptying to the Bay of Bengal. The Teesta River originates from the Pahunri (or Teesta Kangse) glacier above 7,068 metres (23,189 ft), and flows southward through gorges and rapids in the Sikkim Himalaya. Teesta is the lifeline of Sikkim as the river Ganga is for the North Indian plains.
The river and valley must have been made for each other. I have rarely seen things in my life so nicely supplementing, complimenting and blending with each other … the mountains, the Teesta River and its valley. The greenish colour of the water looks lovely and attracts me when i saw it for the first time around 6 years ago. I had never seen water so clear and of such a hue. Since then, I have always looked forward to the first glimpse of the Teesta and the subsequent views of the river on every trip along that road.
While coming down from Gangtok to Siliguri, I took photographs of the Teesta river in its turquoise splendour as we moved down … almost together.
Ever wondered why the river Teesta is so green?
The possible reasons may be the presence of blue-green algae and rock flour or glacial flour (consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion or by artificial grinding to a similar size) in the river. The rock flour is very light and stays suspended in the river for a long time. The sunlight that reflects off this rock flour is what gives the river the spectacular turquoise blue or green colour. Blue-green algae in rivers and streams often lends a greenish colour to the water. Rangeet valley is rich in Limestone and Dolomite, and these minerals are known to give water a green-blue tinge. Rangeet river is the largest tributary of the Teesta river. Some mountain lakes and streams that contain finely ground rock, such as glacial flour, are turquoise.