By isolating I-.Wn clusters in the gas phase, we eliminate the fluctuations and heterogeneity present in solution, allowing us to follow how water molecules (W) sequentially lock into position and form supramolecular complexes at the early stages of hydration: We report vibrational predissociation spectra of the I-.Wn 1 less than or equal to n less than or equal to 3, complexes quenched close to their minimum energy configurations by complexation with argon. Structures are extracted from these spectra by comparison with the band patterns expected for the various geometries.