21 June 1926, O 9, together with the O 11, Maarten Harpertszoon Tromp, Jacob van Heemskerck, Z 7 and Z 8, sailed from Den Helder to the Baltic Sea to visit the port of Kiel, Göteborg and Trondheim.
HNLMS Maarten Harpertszoon Tromp | HNLMS O 9 | HNLMS O 11 | HNLMS O 1 | HNLMS Karel Doorman | HNLMS ''Karel Doorman'' | HNLMS Jan van Gelder |
21 June 1926, O 11, together with the O 9, Maarten Harpertszoon Tromp, Jacob van Heemskerck, Z 7 and Z 8, sailed from Den Helder to the Baltic Sea to visit the port of Kiel, Göteborg and Trondheim.