Thousands of people gathered to take part in performances to show the hospitality of Quang Ninh province, its tourism potential and culture of the sea.
Other activities included a firework display, concerts and fashion shows.
The event has become an annual rendez-vous for domestic and foreign tourists, and is part of the programme to vote for Ha Long Bay as a world cultural heritage site.
The 2009 Ha Long carnival has attracted many international delegations, including those from Laos, China, Indonesia and India.