The page feels balanced. The elements on the left of
the page roughly balance the elements on the right.
The size of the image with the rushing water is
compensated for by the greater intensity of the smaller
pictures.
The page feels unified. The greens in general are
balanced and dispersed across the web page. This
keeps the viewer’s eye interested as in flits from green
to green. One could also say the same about the
whites.
The page has good contrast.  There is an interesting
contrast of size between the photos.
The page feels dynamic. The rushing water over the
rock contributes to an overall feeling of dynamism.
The page has a simple interface. Simple javascript
buttons make the site easy to navigate.
Take a look at this snapshot of a website.