Over recent decades, China has made great strides in advancing military science and research. Submarines, as a crucial part of naval forces, have been hailed as the "underwater blade" of modern warfare due to their stealth and high-tech capabilities.

Seven years ago, Yu obtained official support to produce films about the Chinese navy, with Operation Red Sea becoming the first big-budget title of its kind. Since then, he and director Lam have embarked on a journey akin to scientific research, delving into the lesser-known world of submarines — one of the most mysterious forces in modern military strategy.

Citing Chairman Mao Zedong's famous 1959 slogan, "Even if it takes 10,000 years, we must develop our own nuclear submarines", Yu reveals that their original plan was to create a biographical project about Huang Xuhua, the mechanical engineer hailed as "the father of China's nuclear submarines".

"During a time of extreme scarcity, Chinese scientists independently developed and built our first nuclear submarine," Yu recalls, reflecting on how he was deeply moved by the dedication and devotion of the country's first-generation submarine designers.

However, believing that today's audience — especially younger viewers — are more eager to see what China's modern naval nuclear submarine forces look like, Yu and Lam decided to shift the storytelling to a contemporary setting.

As a leading figure in the action film genre, director Lam had previously collaborated with Yu on other blockbusters like Operation Mekong and The Battle at Lake Changjin.