China’s first submarine unit using air-independent propulsion (AIP) technology recently broke a number of records set by the Chinese navy, Science and Technology Daily recently reported.

Records such as the longest sailing distance, maximum submergence depth and sinking target ships under boundary conditions were all broken by the unit.

Military commentator Zhang Haixiong disclosed that submarines equipped with AIP technology prolong operation duration underwater to about two or three weeks, indicating the increasing stealth of the submarines.

The time a conventionally powered submarine can spend underwater ranges from 10 to 100 hours, as they need to surface regularly to charge. However, submarines can be charged underwater if they are equipped with the AIP system.

Zhang noted that AIP submarines, with higher combat effectiveness, are second only to nuclear submarines, adding that although AIP submarines are more expensive right now, in the future they will become the conventional option.