One of the most spectacular sights in the world, the Aletsch Glacier is a famous river of ice that cuts its way through Switzerland's Alps. With a good weather window, I was able to capture the size and scale of this 23-kilometre glacier just as the last rays of sun disappeared for the day. With clouds to provide a natural diffusion for the sunlight, the colours of the deep pack-ice revealed a rich aqua-blue that can really only be appreciated in person. These photos attempt to do justice to this marvel of nature.