The role of natural environments, especially ‘green space’, in promoting human health and well-being is well-researched. However, less is known about the benefits of ‘blue space’ (e.g. the coast) or ‘managed’ nature (e.g. zoos). In this thesis, six studies investigated the restorative potential of sub-aquatic settings, specifically public aquariums and the biological diversity within them. Studies 1 and 2 investigated preferences for, affective responses to, and the restorative potential of, five built and natural settings (i.e. built, green space, blue space, natural underwater and public aquariums). Using the same measures, Study 3 focused solely on people’s responses to aquarium exhibits, sub-categorised by geographic region, level of species richness and abundance, and taxonomic group. Study 4 examined behavioural, physiological and psychological responses to one aquarium exhibit during three stages of restocking. Finally, to establish how perceptions of species richness and abundance influenced well-being outcomes, people viewed and evaluated either one (Study 5) or two (Study 6) large aquarium exhibits. These studies found that natural sub-aquatic and aquarium settings were as preferred, and perceived as potentially restorative, as green space environments, and different exhibits elicited different responses: ratings were higher for tropical exhibits (vs. temperate), high abundance (vs. low) and vertebrates (vs. invertebrates), although findings for species richness were mixed. Within one exhibit, higher stocking levels resulted in increased attention and interest, greater improvements in mood, and some physiological evidence of relaxation (e.g. decreased heart rate). Broad levels of marine life could be distinguished but estimates of actual numbers were poor. Viewing one or two exhibits tended to improve mood, decrease arousal and be perceived as restorative; any differences between the two exhibits were more evident when both had been viewed. Overall, findings suggest that engaging with different types of managed nature may provide valuable perceived human health and well-being benefits.