Synopsis: The spinner dolphin (Stenella longirostris) is a pantropical species with global distribution.  It has been studied in some detail in the Pacific and south Atlantic, but very little is known of this species in the Red Sea.  The Red Sea is one of the least ecologically disturbed seas compared to other enclosed marine habitats and much of the region remains unexplored.  However, current anthropogenic impacts are on a rise and so is the concern about long-term viability of coastal species and habitats.  During my PhD study, I have investigated the population parameters, size and structure, site fidelity and socio-behavioural dynamics, and various aspects of the life history of spinner dolphins frequenting a small offshore protected area, Samadai Reef, off the coast of Egypt.  I applied the commonly used photo-ID mark-recapture technique, but contrary to most other similar studies, I collected my data exclusively underwater, which allowed me to record rarely obtainable socio-demographic and early postnatal developmental data.  Furthermore, genetic data (miniature skin biopsy samples) were also collected for future population genetic analyses.  Using a combination of photographic, photogrammetric, and focal behavioural techniques, my postgraduate study has quantified several fundamental life-history traits of the Red Sea spinner dolphins, as well as population parameters, group structure and socio-behavioural dynamics of the dolphins frequenting the region of Samadai Reef.  As a conservation biologist at heart, I have always been interested how socio-demographic and ecological factors influence population processes and patterns of geographic fidelity, especially in sites known to be of vital importance to the animals’ daily activities, such as the spinner dolphins’ resting sites.  As active member of research team involved in 'Sustainable Development in the Southern Egyptian Red Sea' project, funded by the Italian Cooperation, my work contributed new data directly applicable in the formulation of conservation policies, such as responsible eco-tourism (dolphin/whale watching, etc.) in the Egyptian Red Sea.