The Dragon Boat Festival, also known as Tết Đoan Ngọ
Today, in Vietnam, is the Dragon Boat Festival, known in Vietnamese as Tết Đoan Ngọ. It is celebrated on this fifth day of the fifth lunar month, similar to its Chinese counterpart. It is also called "Mid-year Festival" and holds cultural significance as a time to ward off evil spirits and diseases. Typically, it involves lots of eating of sticky rice dumplings, fruits, and fermented glutinous rice, which are believed to kill parasites in the body. One person I spoke to called it the holiday of worms as it is the day to cleanse out all of the intestinal parasites by eating special food. People often perform ritualistic cleansing around the house as well as perform special prayers for health and protection.
Vietnam only has a few dragon boat races in some of the major cities to honor their ethnically Chinese citizens. For ethnically Vietnamese, the holiday is more about offerings and eating. Offering tables like you see above are very common. It is a common sight today to see women carrying around large bouquets of yellow flowers as they come home for the home offering. In Vietnam, the dragon boat festival is mostly about eating and offerings and not as much about dragon boats.
I found this very interesting website which goes into detail about the holiday if you are interested in learning more.