We present novel existence results of 3d gravity-capillary periodic traveling waves, in particular, concerning bifurcation of multiple, geometrically distinct truly 3d Stokes waves having the same momentum of any non-resonant 2d Stokes wave. This unexpected clustering phenomenon of Stokes waves, observed in physical fluids, is a fundamental consequence of the Hamiltonian nature of the water waves equations, their symmetry groups, and novel topological arguments.