A German research organization is searching for an underwater environmental monitoring station that was moored on the sea bed and went missing last month.

The device, which measured water flow and methane concentrations among other things, was located 22 metres under the surface in a restricted area of Eckernfoerde Bay where no boats are allowed. The bay is in northern Germany, off the Baltic Sea.

The observatory weighed some 740 kilograms and was moored by thick cables. It was worth the equivalent of about $450,000 Cdn, BBC News reported, but researchers said the data it collected as "priceless."

The power supply for the observatory as it was being deployed in 2016 in a restricted area closed to boats. (Research Dive Center of the CAU)

The Geomar ocean research centre says data transmission ended abruptly Aug. 21. Researchers first suspected a transmission failure, but divers sent down last week discovered that the equipment was missing and saw only a frayed cable.

In a news release in German, the centre said the observatory was "removed with great great force" from its position, and the cables were so thick that storms, currents or marine animals could not have detached it.

Wer hat unsere <a href="https://twitter.com/hashtag/Messger%C3%A4te?src=hash&ref_src=twsrc%5Etfw">#Messgeräte</a> gesehen? Am 21.8. wurden die Geräte der <a href="https://twitter.com/HZG_de?ref_src=twsrc%5Etfw">@HZG_de</a>/<a href="https://twitter.com/hashtag/GEOMARMessstation?src=hash&ref_src=twsrc%5Etfw">#GEOMARMessstation</a> bei <a href="https://twitter.com/hashtag/BoknisEck?src=hash&ref_src=twsrc%5Etfw">#BoknisEck</a> offenbar entfernt. Die Taucherinnen und Taucher des Forschungstauchzentrums <a href="https://twitter.com/kieluni?ref_src=twsrc%5Etfw">@kieluni</a> fanden nur noch das zerfaserte Landanschlusskabel...<a href="https://t.co/06gpV6gFnL">https://t.co/06gpV6gFnL</a> <a href="https://t.co/0wyxwf9RGb">pic.twitter.com/0wyxwf9RGb</a> —@GEOMAR_de

News agency dpa reported Thursday that Geomar said divers took a second look this week and found only parts of the station's supports. Police are investigating.