  We present the first results from an on-going survey to characterize the
circumgalactic medium (CGM) of the massive high-redshift galaxies detected as
submillimeter galaxies (SMGs). We constructed a parent sample of 163 SMG-QSO
pairs with separations less than $\sim$36 arcsec by cross-matching
far-infrared-selected galaxies from Herschel with spectroscopically confirmed
QSOs. The Herschel sources were selected to match the properties of SMGs. We
determined the sub-arcsecond positions of six Herschel sources with the Very
Large Array and obtained secure redshift identification for three of those with
near-infrared spectroscopy. The QSO sightlines probe transverse proper
distances of 112, 157, and 198 kpc at foreground redshifts of 2.043, 2.515, and
2.184, respectively, which are comparable to the virial radius of the
$\sim10^{13}$ Msun halos expected to host SMGs. High-quality absorption-line
spectroscopy of the QSOs reveals systematically strong HI Lyman-alpha
absorption around all three SMGs, with rest-frame equivalent widths of
$\sim2-3$ \AA. However, none of the three absorbers exhibits compelling
evidence for optically thick HI gas or metal absorption, in contrast to the
dominance of strong neutral absorbers in the CGM of luminous $z \sim 2$ QSOs.
The low covering factor of optically thick HI gas around SMGs tentatively
indicates that SMGs may not have as prominent cool gas reservoirs in their
halos as the co-eval QSOs and that they may inhabit less massive halos than
previously thought.
