(1)The underwater Xifengkou Great Wall has lost much of its grandeur. It is silent and gentle, under a coat of green alga. It became pitch black 20 meters below the water and the only sound was that of our breathing. (2) Soon enough, I came across a watchtower. Upon entering, the light could hardly penetrate the dark water. (3)As time went by, several houses constructed by backing the Wall appeared in front of me. There were even cooking benches and kang (heated brick beds) inside them. (4) Not until October 2009 did we discovered this arched gateway 50 meters under the water. I was crying out excitedly inside my head—in the distance, I realized that we had found the south gate of the Xifengkou Fortress.