This is the last of my posts on the Onondaga. These are images of the areas where white light cannot be used during some periods of time, the one restroom included.They are afraid that some moron forgets to switch the light off after the dropping, and the enemy can see it (the light, I mean). Red lighting is only switched on if the submarine is surfacing at night. This allows the eyes of the Officer of the Watch, and any lookouts, who will be going up on the bridge to adjust to the darkness before going up. Submarines use red lights inside for the same reason as ATC, aicraft control towers, planetariums, and some movie theaters use them. Your eyes adjust more quickly from red light to darkness than other color lighting. A red light has been the traditional choice for retaining night vision since before WWII when the military settled on red as the best choice. Recently, there has been a move to green and blue-green light, precipitated in large part by the military's change to green, which itself has been primarily motivated by the increased use of night vision equipment. As it turns out, green light also offers some advantages over red as a means to retain night vision capability. However, it isn't so easy. In fact, if you have a brighter light than you actually need, a brighter green light will generally have a more negative effect than an equally bright red light. Green or blue-green has a greater capacity to adversely effect night vision because the eye is about 100 times more sensitive to these colors, so even moderately too bright light can have a serious deleterious effect. Submarines, at least US subs, don't use red lights. Instead of "rigging for red", the control centers and SONAR shacks rig for "low level light." Red was found to cause aggression and blue was depressing (and hid some colors on the green waterfall displays). SONAR is always rigged this way and the control center does this before moving to periscope depth in the evenings, nights and early mornings. Red light has minimal effect on night vision because its energy level is so low that the eye doesn't register it strongly enough to produce a compensatory reaction. Red light has the longest, slowest wavelength of any form of visible light and thus the least energy--as you shift toward the blue end of the spectrum, wavelengths shorten and energy levels rise. Thank you for your kind comments.