From Longman Dictionary of Contemporary Englishunderseaun‧der‧sea /ˈʌndəsiː $ -ər-/ adjective [only before noun] HEOhappening or existing below the surface of the sea → submarine undersea exploration
Examples from the Corpus
undersea• But what if the message happens to go by undersea cable?• It was an undersea face; the eyes were only part of an inflated bag of venom behind it.• The bacteria that inhabit the undersea hot springs fall into this group.• Tsunamis are caused by violent oceanic events such as earthquakes, undersea landslides, volcanic explosions, and impacts.• Holystone and Desktop, for instance, designate several highly sensitive undersea operations.• Much of the evidence comes from studies of ancient trees and undersea terrain.• Players direct Freddi and Luther on an exploration through the animated undersea world in search of materials for the trap. 