This colorful photograph shows the drillers testing the underreamer to determine how much water pressure is needed to fully extend the arms. The underreamer arms are used to enlarge the borehole to a diameter greater than the bit. The spray of the drill water is tinted by the yellow glow of the sodium vapor lights. (Credit: Bill Crawford, IODP/TAMU) [Photo ID: exp351_061] Back to expedition photos.