Grabbing the handle and giving it a twist, Chu Mingcheng didn't know that the handle, corroded by years of seawater, was already jammed.
Chu Mingcheng felt the handle was loose and, with a gentle tug, pulled it off completely.
The lock's core was dead, but the wooden door had softened.
Chu Mingcheng simply kicked the door in, creating a hole big enough to pass through.
He didn't go in immediately but waited outside for a bit, waiting for the murky water to clear again and for anything that might be inside to swim out.
This thing, of course, wasn't anything fantastical.
Chu Mingcheng was worried there might be some venomous marine life inside and that rashly entering could be troublesome, so he didn't go in right away.
After a little while, he didn't see anything swim out, so he slowly approached the doorway, shining his flashlight inside and surveying the entire room.