Vagn Walfrid Ekman (May 3, 1874 - March 9, 1954) was a Swedish oceanographer.
Born in Stockholm to Fredrik Laurentz Ekman, himself an oceanographer, he became committed to oceanography while studying physics at the University of Uppsala and, in particular, on hearing Vilhelm Bjerknes lecture on fluid dynamics.
During the expedition of the Fram, Fridtjof Nansen had observed that icebergs tend to drift not in the direction of the prevailing wind but at an angle of 20°-40°. Bjerknes invited Ekman, still a student, to investigate the problem and, in 1902, Ekman published his theory of the Ekman spiral which explains the phenomenon in terms of the balance bewteen frictional effects in the ocean and the fictitious forces arising from planetary rotation.
On graduating in 1902, Ekman joined the International Laboratory for Oceanographic Research, Oslo where he worked for seven years, not only extending his theoretical work but also developing experimental techniques and instruments such as the Ekman current meter and Ekman water bottle.
From 1910 to 1939 he continued his theoretical and experimental work at the University of Lund.
A gifted amateur bass, pianist and composer, he continued working right up to his death in Gostad, near Stockaryd, Sweden.