The naked eye is also an excellent instrument for probing the dark lanes of our own galaxy. If the Milky Way is bright, you can generally seen large patches of darkness amid the sea of stars. There are several other phenomena that you can look for without optical aid. They are best observed shortly after sunset or before sunrise when the light from the sun is illuminating the space immediately overhead. If you have a dark northern view you can search for aurorial displays.
Some displays are very spectacular and fill the entire sky.
But many displays are not that extensive and are easily missed. If you specifically spend time looking for aurora you might be surprised at how often you can see it. It follows the ecliptic and is due to sunlight scattering of dust particles orbiting the sun. This is a faint patch of light, similar to the Zodiac light, except that it occurs exactly opposite the sun in the sky. This only occurs when the atmospheric conditions allow it.