While we report reorientation times (in agreement with NMR) and H-bond exchanges, these earlier works consider residence times-which rely on criteria (e.g., site definition, treatment of transient escapes) that can significantly affect the results All the key identified features-overall shape of the jump time distributions, nature of the sites with slowest dynamics, split in hydration dynamics of RNA phosphate oxygensare very similar in the two studied sequences, GGGG and GCGC (see Fig. and Fig. ).