The archipelago lying off the West coast of Estonia, made of two fairly important islands (Saaremaa/ Ösel in Swedish, and Hiiumaa/ Dago) is, in many ways more comparable to the big Swedish islands of the central Baltic (Öland and Gotland) than to the Danish archipelago lying east of the Jutland peninsula. Like their Swedish counterparts, they are real maritime low bare limestone plateaux (comparable to the French «causses»), covered with poor quality vegetation, mostly shrubs (mainly junipers) or forests (pines) on thin mediocre soils, with difficult climatic conditions owing to violent winds. The physical conditions of the Danish islands are more favourable to agricultural activities. Whereas throughout history the resources of the Estonian islands have been quite limited, in terms of forestry and agriculture (in spite of active craft industries), their location near the important maritime ways giving access to the gulfs of Finland and of Riga has attracted political and commercial powers, who wanted to assert themselves in the Baltic area: Danes, Germanic orders of knighthood, Swedes, and last but not least Russians, who dominated the local Finno-Ugrian-speaking populations that has settled in those islands at the beginning of the Christian era. If the maritime traffic of the small Estonian islands has never been very important, unlike that of the mainland like Haapsalu and Pärnu/ Pernau, who were for a long time under Hanseatic domination, fishing has always been a major activity, particularly in Hiiumaa, constituting one more source of income for the people living along the coast (in a wide sense) and who practised fishing alongside agriculture in varied proportions. As in the two big Swedish islands of the Baltic, the limited potential of resources (added to the probable consequences of the harsh conflicts over military and political control of those strategically-situated islands) accounts for the present decrease of the population, also affected by the two world wars and fifty years of Soviet repression. Unlike the Danish archipelago, the two main Estonian islands are not densely populated, nor do they possess big cities, nor can they boast of highly-developed and intensive economic activities. Kuressaare, the major city of Saaremaa, the main island, is a «museum-city», the equivalent of Visby in Gotland, although it cannot be compared to the big urban structures of the Danish archipelago. As a result, there is much to say about what those islands have been through (like mainland Estonia in many ways), since the arrival of the first Christian missionaries in the Xllth and XIHth centuries. Despite their relatively favourable geographical situation, which was not devoid of danger up to a recent past, they have never thrived, unlike the islands situated east of Jutland, which have always made of Denmark the «keeper of the straits» and possess Copenhagen, among the other rich cities of Northern Europe.