As one of the biggest-budget upcoming films, Operation Leviathan is scheduled to be released on Jan 29, the first day of the Year of the Snake.

It is a follow-up to Hong Kong director Dante Lam's blockbuster Operation Red Sea, the highest-grossing film of 2018, which raked in a staggering 3.65 billion yuan ($500.1 million) at the box office.

For the new film, the elite assault team Jiaolong (dragon) reunites to face a more perilous mission in the fictional Republic of Ihwea, which has emerged from the quagmire of civil war only to be threatened by terrorists backed by a powerful foreign country.

Using a life-size prop submarine 110 meters in length, the film includes an underwater submarine battle, with the actors playing the navy officers and soldiers having undergone intensive training ranging from combat skills to gun usage and diving techniques.

Du Jiang reminisced about the challenges posed by the massive prop, which was too large to be kept outdoors as it attracted many curious tourists during the filming of the movie in Qingdao, Shandong province.

Yu Dong, the founder of Bona Film Group, said that the large tank dug for the ocean scenes was capable of generating waves. Despite filming taking place in winter, with temperatures plummeting to -10 C, the actors performed their stunts without the assistance of doubles.

China's first deep-sea war-themed blockbuster, the movie was filmed in IMAX and when shown on an IMAX screen, contains 26 percent more content than a standard screen.