Additionally, the production utilized soundstages covering a total of 46,000 square meters, over 8,000 square meters of workshops and, at its peak, employed up to 1,500 crew members. A total of 16 types of submarine-related weapon props were created, along with 10 different Jiaolong Squad uniforms designed to suit various combat environments.

During filming, Lam maintained his signature style — bold, relentless, and pushing the limits. He personally operated a camera, diving deep with the actors for underwater scenes and joining them in wirework stunts for submarine rollover sequences.

Yu recalls that when he visited the set in Qingdao during winter, he was still shivering from the cold even while wrapped in a thick coat.

"At the time, the director strapped himself in with just his feet on the wire rig, hanging completely upside down while holding the camera to film underwater," Yu adds.

"Although a massive boiler was installed by the pool to raise the water temperature, it was still difficult to make it feel warm given the outdoor conditions. When everyone got out of the water, they were shivering, spraying hot water over themselves to warm up. After an entire day of filming, the footage captured might only amount to a few seconds in the final cut. To complete the sequence, they endured these conditions for more than 10 days," shares Yu.

According to data from the popular movie database IMDb, Operation Hadal was also released in Singapore and the United States.

When asked about expectations for overseas markets, Yu expressed hope that the new movie will showcase the rapid progress of the Chinese film industry, while also raising interest in Chinese stories among more foreign audiences.