Harbour of Gdynia, Poland still dangerous for ships due to mines and wrecks according to a CIA report dated 9 December 1946

An item reported that the efforts to clean the Polish waters from mines was still executed by the Russian navy while the Polish sailors were lacking the necessary experience. The harbour of Gdynia was still unsafe for ships while mines and sunken vessels were still hardly removed.

Source
The report was published on www.archive.org, document number CIA-RDP82-00457R000100820009-5