"Received! Lin, be careful! Again, your mission is just reconnaissance!" Mike's voice was filled with concern.
Lin Yu'an took a deep breath and bit into the regulator mouthpiece. He turned back to Riven and made an "OK" gesture, then let his body sink down, slipping into the unknown dark entrance like a silent fish.
Riven watched as his beam of light and the bubbles he exhaled quickly disappeared into the depths of the cave, leaving her alone in the world in an instant.
She clenched the Glock in her hand, pressing her ear tightly against the cold rock wall, listening for any slightest movement from underwater and the surrounding environment, starting an unbearably lengthy and tormenting wait.
...
The world underwater is another universe.
Upon entering the entrance, all external sounds were instantly cut off.
The only thing Lin Yu'an could hear was his own calm yet deep breathing—amplified through the regulator into a clear "hiss—inhale—", standing out in the ancient silence.
