The opening ceremony of the 33rd Southeast Asian Games was held in grand fashion at Rajamangala Stadium in Bangkok on Tuesday night (December 9, 2025). Running from December 9 to 20, 2025, the Games mark Thailand’s seventh time hosting the regional multi-sport event.
This year’s edition features a modern, environmentally friendly, and technology-driven concept showcased prominently throughout the opening ceremony.
However, just a few hours after the spectacular opening, public attention shifted to Cambodia’s sudden decision to withdraw its entire contingent following an escalation in border tensions.
A Grand Opening with a Green Concept
More than 50,000 spectators filled the stadium from the afternoon onward. The ceremony opened with thousands of drones forming ocean-themed visual displays, in line with the official theme "We Are One, Connected by the Sea".
The opening began with a moment of silence in remembrance of Queen Sirikit, who passed away in October 2025.
A water spectacle became the main highlight as a massive pool emerged at the center of the field, featuring synchronized performances by female swimmers alongside jet ski and flyboard displays. Thailand promoted the concept of a “Green SEA Games,” including the lighting of an environmentally friendly torch carried by Panipak Wongpattanakit, a two-time Olympic gold medalist.
The ceremony was divided into five segments, tracing the history of the SEA Games and the evolution of modern sports. The segment titled Return to Origins highlighted the inaugural SEAP Games held in 1959, while We Are One showcased large-scale water choreography and immersive visual projections.
Artists such as BamBam of GOT7, Violette Wautier, Hero Srimok, and Twopee added to the festive atmosphere with live performances.
King Maha Vajiralongkorn officially declared the SEA Games open following a speech by the prime minister. Thailand’s delegation, the largest at the Games with 1,535 athletes, entered the stadium last.
Vietnam, meanwhile, appeared earlier in the parade of nations, led by flag bearers Le Thanh Thuy and Le Minh Thuan.
SEA Games 2025 Brings 13,657 Athletes Across ASEAN
The 2025 SEA Games feature competitions in 51 sports and will run until December 20. Several events, including football, badminton, and baseball, had already begun even before the official opening ceremony.
A total of 13,657 athletes from all 11 ASEAN countries are competing at the 2025 SEA Games. The Games feature a variety of Olympic disciplines and traditional sports unique to the region.
Thailand fields the largest contingent with 1,531 athletes, followed by Myanmar (1,477), the Philippines (1,168), Malaysia (1,166), and Indonesia (1,021). Singapore has sent 930 athletes, followed by Vietnam with 842 and Laos with 598. Meanwhile, Timor-Leste is represented by 110 athletes, Cambodia by 84, and Brunei Darussalam by 65.
Badminton was the first sport to award medals at the Games. Under the competition format, the two losing semifinalists in the team event each receive bronze medals. The first medal of the 2025 SEA Games was therefore claimed by Singapore, which secured bronze in the women’s team event.
Cambodia Withdraws Over Security Concerns
Less than 12 hours after the opening ceremony, the National Olympic Committee of Cambodia (NOCC) sent an official withdrawal letter to the organizers.
NOCC Secretary General Vath Chamroeun said the decision was taken in response to increasing requests from athletes’ families for their immediate return. “This decision was not made lightly,” Chamroeun wrote in the letter.
Border tensions between Thailand and Cambodia have been escalating since July and peaked on December 7. Air strikes and exchanges of fire resulted in casualties on both sides, including six Cambodian civilians and one Thai soldier. The total death toll reached 10, while more than 140,000 people were displaced.
Prior to the full withdrawal, Cambodia had already reduced its participation from 21 sports to 12. Men’s football, sepak takraw, and several martial arts disciplines had been dropped from the program since late November.
Although Cambodia’s swimming, taekwondo, and ju-jitsu teams were present during the flag-raising and opening ceremony, the final decision to withdraw was confirmed on Wednesday morning.
Organizers are now required to adjust competition schedules for several sports that were scheduled to begin that day, including swimming, ju-jitsu, taekwondo, and gymnastics.
Thailand had previously assured enhanced security measures for Cambodian athletes, but conditions on the ground ultimately proved insufficient to prevent the complete withdrawal of the contingent.
As a result, the 2025 SEA Games officially began under the shadow of a regional crisis looming over Southeast Asia’s largest sporting event.
