[Seaplanes]

The WL-UGUV registration proves that the photo was taken after 1 January 1939, the date of the introduction of the WL- replacing D- on Luftwaffe non-operational aircraft. This system was terminated towards the end of 1939 and reverted to D- only. However, things take time and many aircraft flew with WL-registrations well into 1940. My reference is made to BA/MA RL 2 III/1328.
I can also add that on 3 November 1936 D-UGUV (W.Nr. 4238) was transferred from E-Stelle (See) Travemünde to Junkers, Leipzig for repairs or overhaul.