The oil lamp here is identical to the lamps in the guardhouse.

The doors are kept locked to prevent access into or out of the caverns.

The <evil priests> in areas 42, 44, and 65 have keys. In each door,
2 of the 3 keyholes are fakes; sticking a key in one of them
turns a dummy lock that activates a chime. Ringing a chime risks
drawing attention but otherwise has no ill effects. On the north
door, the real lock is in the middle keyhole. On the east door, the
real lock is at the bottom.

A door can be unlocked with the proper key or by picking the lock
(although picking a fake lock triggers the door’s chime, as noted
above). A knock spell opens a door. A character can force the
door with an Open Doors roll, but reduce the chance for success
by 1. A successful Bend Bars/Lift Gates roll also forces the door.
The party can beat the door down with weapon attacks; the door
can withstand 40 points of damage before splintering.

The pool contains a natural spring that keeps the water in motion.
A tiny natural channel drains the water into area 56. The pool is
home to a water weird, which attacks any creature that lingers in
the chamber for more than 1 round. Any delay, such as searching
the pool or fiddling with the doors, triggers an attack.

Water Weird: AC 4; MV 12”; HD 3+3; hp 16 <19>; #AT 1; D nil; SA
attacks as a 6 HD monster, a hit forces a save vs. paralyzation to
avoid being pulled underwater; SD being reduced to 0 hit points
or fewer causes the weird to dissolve and reform in 2 rounds,
only blunt weapons deal full damage (other weapons deal 1 point
of damage), slowed by cold, fire deals half or no damage, purify
water slays, other energy or magical attacks are ineffective.
<THACO 13>
<XP 438>

>>56.