She came first in the time of 8:35:55, leaving Thai runner-up A. Himathongkom far behind who finished at 8:45:44. N. Jungkrajang, also from Thailand, came third clocking 8:51:09.
Another Vietnamese swimmer, Le Thi My Thao, ranked 9th out of ten athletes in this category.
Vien previously won a gold in the women’s 200m individual medley the same day and secured three other golds in the women’s 100m and 200m backstroke and 400m freestyle on August 21-22.
Vietnam aims for 49-59 gold medals in this SEA Games to rank in the top three.