15
As you step up to the water's edge and gaze into it, a pair of large creatures leap from underneath the surface.
The door slides closed behind you, and you slowly start to ascend. After several minutes, the chamber grinds to a halt, and the door slides open again.
Seconds after you push the button, the a hidden door seals the chamber, and you start to descend. 
Although you do not know your rate of descent, you notice, once you stop, that the entire trip required three minutes, and that the chamber made several direction changes during that time.
The chamber comes to a stop, and the door slides open. Through the dim waters (which can be seen through the walls of the dome to the south), three other illuminated domes can be seen, one large building ahead, and a smaller dome on either side of it...
A thick metal door slides shut behind you. Ten seconds later, the floor and ceiling begin to radiate a bright red light, and powerful blasts of air rush out of both grillworks. After 20 seconds, the process ceases.
You fiddle with the console buttons, but nothing of any note happens. It probably takes a trained person to operate the machinery.
You hear a faint click, and suddenly water begins to rush in through the grillwork!
You hear a high pitched humming noise, and the water level slowly begins to recede
As you push the button, you hear a strange whirring noise, and the parabolic reflector on top of the dome inches upward.
As you push the button, you hear a strange whirring noise, and the parabolic reflector on top of the dome inches downward.
Pushing this button causes the reflector on top of the dome to rotate in a clockwise manner.
Once you push this button, a red light comes on. Six seconds later, a green light comes on.
When you push the button, a low droning sound is heard beneath the floor. Then the crystal column glows a bright purple and a bolt of blue light shoots out of the parabolic reflector (a laser unhampered by the light retarding effects of water).
The worker androids pull pistols out from under their clothing and retaliate!