Interesting; you've managed to demonstrate two effects of simultaneous contrast with a single map. Simultaneous contrast is the way some colors will interfere with the perception of adjacent colors. In the second case, the coastal lines, the darker lines appear to desaturate because they're surrounded by a field of the same hue at a greater brightness. The bright blue of the water disguises the dark blue of the lines. They definitely are blue, though, as can be seen if you compare them to the dark gray of the coastline itself.
The other effect, pointed out by Arsheesh, came from placing very saturated complementary colors next to each other. This is usually known as color vibration, and it is worst when you're dealing with thin lines and bright colors. Sometimes it gives the viewer a little bit of eyestrain, which can manifest as a headache. Sometimes it causes the lines to appear to shake, thus the term "vibration." Sometimes it creates a false perception of white or gray lines between the colors, an effect of your visual cortex trying to maintain distinction between the colors. If you want an egregious example, take a look at this image: http://www.bryanray.name/illustration/090219Orrery.png
I'm not going to post that into the thread because it really is rather hard to look at.