Deep brain stimulation begins by doctors drilling two small holes in the head of the patient.

VOA: special.2009.02.03

Seeds should be planted two and one-half centimeters deep.

VOA: special.2009.03.24

He tested the free-diving self-propelled submersible - one of only two in existence at the time - on increasingly deep dives off the California coast.

VOA: standard.2010.06.21