In 1909-11 Robert Lloyd Praeger brought a team of 100 scientific specialists from all over Europe to map the flora, fauna, geology and archaeology of Clare Island, a small, exposed Atlantic island off the west coast. The gathering led to the publication of the path-breaking 'Clare Island Survey'. A century later the survey was repeated as the 'New Survey of Clare Island' (1992-2009) and both works were published extensively by the Royal Irish Academy. This sixth volume provides the most comprehensive description of Irish freshwater and terrestrial algae published to date. Clare Island is one of the few known 'hotspots' of algal diversity in the world. As a result of extensive surveying by a team of specialists, the island is now one of the most intensively worked sites in Ireland and Britain. It has an amazingly rich algal flora, encompassing well over 700 species. The volume's arresting illustrations will intrigue amateur natural historians as well as providing an important reference work for academics and professionals involved in water quality.