Despite the vital roles that marine microorganisms have in the global ecosystem — such as driving the biogeochemical cycles that affect climate and the cycling of elements and nutrients to other organisms — the marine environment remains woefully under-explored. Until recently, the study of oceanic environments was hampered by significant technical hurdles, but during the past decade the advent of new technologies has enabled microbiologists to study in unprecedented detail how marine microorganisms live, participate in oceanic ecosystems and die.

To mark the significant progress that is currently being enjoyed by this field, this issue of Nature Reviews Microbiology is a Focus issue on Marine microbiology, and contains a collection of specially commisioned Reviews and Perspectives that are designed to inform readers of the latest advances and how they are leading to a new understanding of biodiversity, ecology and biogeochemistry. The articles are available to download free owing to the generous support of the Gordon and Betty Moore Foundation and the Agouron Institute. An accompanying Web Focus draws together relevant content from across the Nature Publishing Group (http://www.nature.com/nrmicro/focus/marinemicrobiology).

Also included with this issue is a Nature Outlook supplement that focuses on neglected tropical diseases that afflict poor and marginalized populations. With the drug pipeline for these diseases almost dry, there is an urgent need to develop and deliver new and effective therapies. Unfortunately, despite renewed efforts over the past 10 years — largely driven by a huge increase in philanthropic funding — the situation for those actively engaged in the front line of the war against these diseases has not noticeably improved. The challenges that hinder scientific innovations from reaching the clinic are complex but can be resolved and are the focus of the Outlook.