From January 2020 to January 2022, temperature, salinity, and oxygen (only July 2020 - April 2021) data were logged with an AANDERAA oxygen sensor 3835 and a SEABIRD SBE 37-SI MicroCAT CT(D) in 10-minutes intervals at GEOMAR (Kiel, Germany) pier at 54°19'48.8N 10°08'59.6E. The sensor system is mounted to a floating platform such that a continuous depth of 1 m is ensured at any time. Oxygen data were corrected for salinity, temperature and depth following the manual for Aanderaa Optodes using the salinity and temperature measurements from the SEABIRD SBE 37-SI MicroCAT CT(D) sensor. After cleaning and other re-boots of the sensor package, temperature, salinity and oxygen data tend to deviate from true values. Hence, 60 minutes of data after any re-boot (after sensor servicing with re-deployment, data download or power failure) were deleted. Two major data gaps (January 2020 – July 2020, April 2021 – June 2021) are due to longer periods when the sensors were serviced in the workshop.