It is the junction of the Songhua River and Heilongjiang. Thus it gains the name of “the mix river”, so people call it “Sanjiangkou”. The Heilong River runs smoothly and magnanimous from the west to the east and the water is greenish black. There are lots of yellow sands in the Songhua River. After converging, the water of the river runs mountains high. With distinct border of the black and yellow water, the water flows to the east for more than five kilometers, which make it a marvelous wonder. The Heilong River and the Songhua River converge in Tongjiang, forming Sanchakou. People used to call it “Sanjiangkou”. After this two river form into one, the flow of water strengthens and the surface of the river broadens. Looking from a distance, the border of the heaven and the surface of the river blurs, backwashes come forth, presenting a majestic and grand view. Standing in the bank of Sanjiangkou and looking around, the islands in the middle of river flickers in our eyes, creating a feeling of illusory.