This thematic issue will cover some of the most exciting advances in ophiolite science. Focus is directed toward ophiolite classification during the formation and destruction of ocean basins; the mineralogy, petrology, and isotope geochemistry of ophiolites; and the trace element behavior of crustal and upper-mantle units in ophiolites. The issue will cover the history of origin, the geochemical and petrological development, and the final emplacement of one of the largest and most studied ophiolites, the classical Semail ophiolite in Oman. Further, for a better understanding of ophiolites in relation to subduction processes, one of the papers deals with the lithological and geochemical development of the Izu-Bonin-Mariana forearc crust as a modern analogue. Finally, the issue will present some of the new and exciting aspects of microbial interaction with the volcanic component of oceanic crust, as observed in ophiolites as old as the young Earth.