The depression is travelling at a speed of 25kph and will enter the East Sea in a couple of days.
Bui Minh Tang, director of the Central Hydro-meteorological Forecasting Centre, warned the depression might strengthen into a storm that comes hot on the heels of typhoon Haiyan.
This depression/storm is forecast to hit the southern part of the East Sea on November 13-14 and affect Vietnam on the following day.
Haiyan, the most powerful storm in the world this year, is battering northern Vietnam after sweeping across the Philippines, killing more than 10,000 people.
This year, Vietnam has been hit by a total of 14 storms and four depressions – a record figure for decades.