Along the Swedish coast a deep channel runs northward from outside the island of Oland; this is entirely cut off to the south and east by a bank which sweeps eastward and northward from near Karlskrona, and on which the island of Gotland stands, but it communicates at its northern end with the Gotland deep, and near the junction opposite Landsort is the deepest hole in the Baltic (420 metres = 2 3 o fathoms).
A defensive alliance with Sobieski (August 4, 1677) was rendered inoperative by the annihilation of Sweden's sea-power (battle of Oland, June 17, 1676; battle of Fehmarn, June 1677) and the difficulties of the Polish king.
Off the south-east coast the place of the skdrgard is in a measure taken by the long narrow island of Oland, but north of this the skrgard begins to widen, and the most considerable fjords are found, such as Bravik, which penetrates the land for 35 m.
Of the large islands in the Baltic and Cattegat, besides Oland, only Gotland is Swedish.
The whole of the island of Oland consists of these strata.