Kenneth Craig Macdonald is an American oceanographer and marine geophysicist born in San Francisco, California, in 1947.

Macdonald grew up in El Cerrito and Richmond, California, and graduated from Harry Ells High School in 1966.

He was awarded a Cecil H. and Ida Green Research Fellowship to work at the Institute of Geophysics and Planetary Physics with James Brune in 1975.

His PhD work focused on the tectonic and magnetic properties of the Mid-Atlantic Ridge on Project FAMOUS expeditions led by Bruce Luyendyk.

[10][11] Their work demonstrated that the inside corner region is an area of diffuse deformation caused by extreme tectonic extension.

The shorter segments are important because they define the scale at which individual volcanoes function on the ridge, which, in turn, control the creation of new oceanic crust and hydrothermal activity[16][17] In recognition of his work he was the first marine geophysicist to be awarded the Cody gold medal and prize for his outstanding work and leadership in the Ocean Sciences as well as election as Fellow to the American Academy of Arts and Sciences, Fellow of the American Association for the Advancement of Science, Fellow of the American Geophysical Union (1995), Fellow of the Geological Society of America (1995) and co-recipient of the Newcomb Cleveland Prize for the most important article published in Science magazine in 1980 for the discovery and analysis of black smoker vents.