Explode

When the tank was 64 metres into the cave, it suddenly lost signal. Even though the camera was blurred out by the white liquid, the signal was stable. But suddenly, the monitor died. It was as if the tank had crossed the line to enter a no-signal zone. The technicians tried everything but could not rebuild the signal. The cave was still as quiet as before. Facing this situation, the frontline did not have much choice. Considering the drone might have coincidentally broken down, the frontline sent the second tank into the cave but similarly it lost signal at 64 metres. Thus they could confirm that the signal would be lost after that mark.