Fribytteren paa Østersøen
transl. by Otto Borchsenius. Kbhvn 1875 (2 ed. 1878, 3 ed. 1906)
There is also an unauthorized translation from 1858, Sørøveren i Østersøen

The Freebooter of the Baltic
transl. by Caroline L. Broomall. Media, Pa. 1891
Free e-version: Hathi trust

Itämeren sissi
transl. by Emil Mannstén. Helsinki 1930
Editions in 1930, 1959 and 1972

Der Korsar
transl. by Valeska Schmidt & Margarete Rabenow. Berlin 1924
"Bearbeitet von Franz Werner Schmidt". Illustrated