The headquarters of the Great Lakes Science Center is located on the North Campus of the University of Michigan in Ann Arbor. Approximately half of the Center's staff are located in Ann Arbor and half are located at one of the Center's field stations. The Center has five field stations, one vessel base, and three field station/vessel base combinations dispersed throughout the Great Lakes Basin. Strategic placement of the Center's field operations facilitates research conducted over this large geographic area. Field stations are located at Cortland, New York (Tunison Laboratory of Aquatic Sciences); Millersburg, Michigan (Hammond Bay Biological Station); Munising, Michigan; and Porter, Indiana (Lake Michigan Ecological Station). A mid-lake vessel base is located at Cheboygan, Michigan. Combined field stations and vessel bases are located at Ashland, Wisconsin (Lake Superior Biological Station); Oswego, New York (Lake Ontario Biological Station); and Sandusky, Ohio (Lake Erie Biological Station). Research support for ongoing projects is provided through the headquarters location. Descriptions of our research vessels are also included.