Thor was a hydrographical research vessel built in 1930 for Swedish biologist fil.

dr L. Gunnar Sjösted (1892–1975), teaching college, Kristianstad, Sweden for use in marine biological studies in the Sound/Øresund.

[1] Sold in 1933 to the Danish Captain Alf Trolle and refitted for use in polar waters.

The refitting was substantial and included installation of a new engine (30 Hp Bolinder hot bulb engine), electric generators (12/18V, 50A, and 110V, 2 kW; Titan, Copenhagen), electric winches for anchor and a 4000 m hydrographical wire (3.5 mm steel wire), radio (short wave radiotelegraph and MF radiotelephone), echosounder (Echometer, The International Marine Sounding Device, Bruxelles).

[2] Thor was used for two hydrographical expeditions to East Greenland in 1934 and 1935, paid for by the "Alf Trolle and wife's fund in the memory of the Danmark-expedition 1906-1908".