The collisional activation dynamics of hydrated hydroxide clusters in a fast ion beam have been studied upon multiple glancing collisions with argon. Glancing collisions are defined as those involving detectable parent or fragment ions at the end of the beam line. Hydrated cluster ions are ideal for multiple-collision studies because one glancing collision will not on average impart enough energy to dissociate the cluster while two such collisions predominantly lead to dissociation. The absolute values of the attenuation cross section of OH-(H2O)(n=0-4) with argon are 31.6(1.8), 29(2), 25.2(1.4), 33(2), and 50(10) Angstrom(2), respectively. The absolute values of the glancing collision induced dissociation cross sections are 1.17(0.08) Angstrom(2) for OH-(H2O)(1) and 5.7(0.4) Angstrom(2) for OH-(H2O)2. The fraction of single glancing collisions which do not lead to dissociation or loss from the ion beam is 0.92 for OH-(H2O)(1) and 0.25 for OH-(H2O)(2). Single-collision branching ratios of 0.88:0.12 and 0.52:0.46:0.02 have been determined for successive loss of waters from OH-(H2O)(2) and OH-(H2O)(3), respectively. Detachment gives way to dissociation upon collisional activation as several waters are clustered to OH-. Comparison of the hydrated hydroxide attenuation cross sections vs cluster size to those of hydrated hydronium and hard sphere expectations implies that the excess charge of OH- is more localized in water clusters than the proton.