Lake of Sorrow is located approximately 5 km northeast of the city. According to local lore, the lake was named during the war between Vietnam and China. As the story goes, long ago there lived a young couple in this area. They loved each other very much and often met by the lake to enjoy the tranquil setting of this area. At about the time when they spoke of building a future together, Vietnam was in the state of war with foreign invaders from the north. There was a general call for able-body young men to take arms. The young man, Hoang Tung, being extremely patriotic, decided to join the army of king Quang Trung - Nguyen Hue to help defend Vietnam.
The young couple decided to meet by the lake to say their goodbye as Hoang Tung was leaving with his garrison for the north. His betrothed Mai Nuong, being equally patriotic, decided not to be a burden in his mind, lest he won't be able to perform his duties, decided to commit suicide by drowning in the lake. When the time came for the two to meet, Hoang Tung found that she has passed away. The people in this region heard of the young couple's story and decided to rename the lake Ho Than Tho or Lake of Sorrow. Several variations of the story are published. One version along this line claimed that Hoang Tung did not show up at the appointed time. Mai Nuong was heart broken and spent many days by the lake to wait for him. Hopeless, Mai Nuong committed suicide by jumping into the lake.