Fireworks lit up the night sky as nearly 9,000 performers from northeastern Thailand took part in a colourful opening ceremony at the main stadium in Korat, His Majesty the King's 80th Birthday Anniversary Stadium.
The ceremony kicked off with a tribute to King Bhumibol Adulyadej, just a day after the nation celebrated his 80th birthday, in front of Crown Prince Maha Vajiralongkorn.
Eleven nations are chasing a total of 475 gold medals in more than 40 sports at the 10-day biennial showpiece and the host nation has already established an early lead at the top of the medals table.
But the main sports at the Southeast Asian Games start Friday, with attention focused on the athletics competition and the swimming pool, where Olympic hopefuls will be looking to catch the eye ahead of next year's Beijing Games.
The eight-team football competition also resumes Friday, with sides vying for semi-final spots and Thailand gunning for their eighth consecutive success in the competition.
Two years ago, then hosts the Philippines came out on top at the Games, with 113 golds to Thailand's 87. Vietnam won 70 golds and Malaysia took 61.
But the Thais are aiming to increase their haul to 150 this time around and the Philippines have lowered their sights to a more modest 70-gold target.
Organisers announced last month they were removing six sports and a total of 10 events from the competition due to lack of entrants, despite the more than 7,000 athletes and officials confirmed to attend.
As well as the headline events such as football, athletics, swimming and badminton, athletes are competing in a range of lesser-known sports, including the martial arts karatedo and Muay Thai, and sepak takraw, which is similar to volleyball but played with a rattan ball using the feet and head.
Organisers will be looking for a clean Games. Earlier this year they said the event would have the "strictest ever" anti-doping procedures, with twice as many tests as at the Philippines tournament in 2005. The regional anti-doping organisation said it expected up to 10 percent of athletes to be screened.
And they will be hoping to avoid allegations of match-fixing. A Vietnamese court earlier this year jailed two former footballers for rigging a match against Myanmar at the 2005 Games in return for cash from a betting syndicate.
There was also squabbling at the 2005 SEA Games over the fairness of the officiating, with then Thai prime minister Thaksin Shinawatra and other officials expressing doubts after hosts the Philippines took a decisive lead in the medals race.
SEA Games participants are Brunei, Cambodia, East Timor, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam. The Games close on December 15.