Dr. Carol Marcus, director of the Genesis Project, stated that the Starfleet Corps of Engineers, in space suits, dug out a cave within Regula in ten months. The Genesis Device formed the matrix for life in a day, and the lifeforms grew at a substantially accelerated rate.
In Dr. Marcus' proposal to the Federation, she concluded that the potential of the project was to reduce the cosmic problem of food supply. With the device, Dr. Marcus filled the cave with a "lifetime" of food. When she showed Admiral James T. Kirk the cave, she said, "Can I cook, or can't I?" The kinds of life created in the cave were indeed substantial; in addition to the plainly visible vegetation, which provided a breathable atmosphere, there were vegetables and fruits. Also, the chirping of birds could be heard in the cave.
The cave was connected to a supply area with polished floors. When visited by Admiral Kirk, there were cargo containers from Bellus 4 and Kosygin Base in that portion of the cave. The hard-edged environment contrasted sharply with the cave proper. From the storage area, one could pass through a passageway to a scenic overlook of the cave. The overlook opened onto a cliff, where water fell from above. A distance away from the overlook, one could see a body of standing water, which was lit from an unseen source. (Star Trek II: The Wrath of Khan)