Microbes are the engines sustaining nutrient budgets within the Southern Ocean (SO) through their roles in primary production, nutrient remineralization and overall biogeochemical cycling. Besides a good understanding of the nutrient cycling mechanism, a comprehensive understanding of the microbial makeup and key players within these mechanisms are pivotal to accurately predict the impact of future climate change on the SO ecosystem and nutrient budgets. Despite several recent global ocean microbial surveys, the microbial diversity of the vast SO remains limited to single locations or specific regions. We aim to expand the SO microbial diversity knowledge base for the 3 main microbial kingdoms using high-throughput 16S and 18S rDNA tag sequencing. Our study encompasses multi-sectorial sampling at high resolution (1.0 latitudinal intervals) from surface to abyssopelagic depths across multiple SO transects. This study also aims correlate microbial diversity to enviromental and geographical parameters to identify the key drivers of the SO microbial composition.