On a family of arithmetic hyperbolic 3-manifolds of squarefree level, we prove an upper bound for the sup-norm of Hecke-Maaß cusp forms, with a power saving over the local geometric bound simultaneously in the Laplacian eigenvalue and the volume. By a novel combination of diophantine and geometric arguments in a noncommutative setting, we obtain bounds as strong as the best corresponding results on arithmetic surfaces.2000 Mathematics Subject Classification. Primary 11F72, 11F55, 11J25.1 Very recently, a remarkable non-arithmetic approach for classical holomorphic cusp forms was given in [FJK]. 2 Unfortunately, the argument in this work seems to have a gap, specifically the proof of [Ko, Lemma 5.3] is incomplete.Our counting argument is quite different from Koyama's method, though at one point we incorporate a crucial idea from his paper (see Section 11.2).