The ability of some organisms to live in extreme environments has always fascinated us. While more complex species such as mammals can live in very cold or hot surroundings, microorganisms definitely take the crown when it comes to being able to survive the most extreme conditions. These extremophiles are very resilient and can survive conditions that would kill other organisms in seconds. Indeed, some researchers believe that life may have begun with such organisms living deep under the ocean on hydrothermal vents. Helen Albert talks to Professor Rania Siam from The American University in Cairo, Egypt, about her research on microbes living near highly salty underwater ‘brine pools’ in the Red Sea. Helen also discusses the remarkable bacterium Deinococcus radiodurans, which is able to withstand high levels of radiation and desiccation, with Professor Michael Daly from the Uniformed Services University in Bethesda in the USA.