RV Marcus Langseth is a research vessel operated by the LamontâÂÂDoherty Earth Observatory (LDEO) of Columbia University as a part of the University-National Oceanographic Laboratory System (UNOLS) fleet. The Marcus G. Langseth was dedicated on December 4, 2007, came into service in early 2008, replacing the .
Marcus G. Langseth is intended primarily to collect multichannel seismic data, including 3-D surveys. The ship was purchased from the geophysical survey company WesternGeco in 2004, having previously been named Western Legend. The Marcus G. Langseth was named for Marcus G. Langseth, a Lamont scientist.
In March 2009, Chinese authorities denied the vessel permission to pass between Taiwan and China. In August 2009, Marcus G. Langseth was named in a Canadian lawsuit seeking to halt its seismic tomography experiment. The lawsuit was dismissed, diplomatic clearance was issued and the ship sailed after a delay of a day.