First of all: I love swamps!
And further I like "the blue hour", that time of dusk when suddenly the whole world seems to be cast in a blue light. You get it sometimes and at other evenings you don't. Here it seems like you had a "blue hour" and you were in that swamp at the very right time! The clouds pushing in add to the overall atmosphere, and I like the colour contrasts between this blue and the bit of pink in Photo 4 best.