The vast majority of the mid-ocean ridge system and of the continental margins around the globe have not yet been explored. A relatively small number of vent and seep sites have been analysed and are the focus of long-term research programmes. However, the exploration of new areas will certainly provide the discovery of new vent and seep sites. Furthermore, the study of these key locations will lead to the description of new species and improve our understanding of the abundance, diversity, and distribution of species from chemosynthetically-driven systems around the world's oceans. It is the aim of ChEss to develop an exploration field phase to discover new deep-water hydrothermal vents and cold seeps at key locations, to describe their fauna, and to study the processes driving these ecosystems. The main objective is to obtain a thorough understanding of the biogeography of chemosynthetic ecosystems at a global scale. This goal can only be reached through international cooperation, which will be coordinated by the ChEss scientific steering committee. The southern oceans are the less studied regions for deep-water chemosynthetic sites. Mainly, the Indian Ocean Ridges, the southern Mid-Atlantic Ridge, the East Scotia Ridge, and the Chile Rise for vents; and the continental margins of Brazil, Peru, Chile and Africa for seeps, are crucial for the biogeographic puzzle of chemosynthetic systems.