Analysis of the vibrational normal modes (animations available in the ESI) corresponding to the three peak regions described previously provides insight into the water dynamics occurring at these frequencies. In the low-frequency region (below 3 THz), the observed motions correspond to highly-collective vibration of the water molecules in concert with much of the polymer backbone. While the motion of the water molecules is similar in nature to the previously described intermolecular bending in liquid water, the interaction with the polymer backbone leads to a diverse set of modes due to the large number of varying interactions that the water molecules exhibit in this system, with most modes involving external motions (i.e. hindered translations and rotations). Interestingly, a large majority of the observed motions only involve the weakly-bonded water molecules, i.e. those that exhibit either no hydrogen bonding or only a single hydrogen bonding interaction, while those that that are more strongly bound do not participate strongly in the lowest-frequency dynamics.