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Microbial biogeography has become a recognized field of research within the science of microbial ecology. Technological advances such as the high throughput sequencing of genetic information with next-generation sequencing (NGS) technologies have made us able to “see” the diversity of microbial communities. This has considerably improved our understanding that even harsh and seemingly barren environments such as the cryosphere, the frozen parts of our planet, is inhabited by diverse life. This thesis presents three studies in microbial biogeography of the Arctic cryosphere utilizing a range of NGS approaches. The first study of this thesis explores microbial diversity and community composition in snow on North Pole ice floes. It was the first example of 16S rRNA gene amplicon sequencing of North Pole snow. The results of this study showed that snow in different sites on the North Pole can harbor different microbial communities, but these communities are more similar to each other than they are to the surrounding ice and the ocean. The second study confirmed the hypothesis that freshwater networks connected to the cryosphere are inoculated with cryosphere-specific microbial communities. It showed also, that these communities represented about a quarter of the diversity of the microbial community in the estuary. Lastly, this study illustrates the advantages that amplicon sequencing can have over shotgun metagenomics in certain well-defined studies. The final study included in this thesis utilizes the full potential of shotgun metagenomics, which enabled the binning of microbial genomes from metagenomes. Putative genomes showed signs of adaptation to and origin from contaminated habitats. This lead to the hypothesis that the Greenland ice sheet might be a contaminated habitat to a previously unacknowledged degree.The overall aim of this thesis is to illustrate the advantages that NGS has given in the field of microbial biogeography with the Arctic cryosphere as an example. The most important point in the following is that in order to utilize these advantages to their full potential, we need to put emphasis on hypothesis-driven research and acknowledge the caveats that come with NGS in microbial ecology. If we can do this, cryosphere microbial biogeography can be of value not only to us as microbial ecology researchers but also to researchers in other fields and finally to the inhabitants of the Arctic.