  Cluster substructure and ram pressure stripping in individual galaxies are
among the primary evidence for the ongoing growth of galaxy clusters as they
accrete galaxies and groups from their surroundings. We present a
multi-wavelength study of the center of the Hydra I galaxy cluster, including
exquisite new MeerKAT HI and DECam Halpha imaging which reveal conclusive
evidence for ram pressure stripping in NGC 3312, NGC 3314a and NGC 3314b
through compressed HI contours, well-defined HI tails, and ongoing star
formation in the stripped gas. In particular, we quantify the stripped material
in NGC 3312 and NGC 3314a, which makes up between 8% and 35% of the gas still
in the disk, is forming stars at ~0.5 M_Sun yr^-1, and extends ~30-60 kpc from
the main disk. The estimated stellar mass in the tails is an order of magnitude
less than the HI mass. A fourth "ring" galaxy at the same velocity does not
show signs of ram pressure in HI. In addition, we use the HI and stellar
morphologies, combined with a Beta model of the hot intracluster medium, to
constrain the real distances of the galaxies to the cluster center, and we use
the chance alignment of NGC 3314b behind NGC 3314a to break the degeneracy
between whether the galaxies are in front or in back of the cluster. The drag
seen in the HI tails supports our preferred scenario that NGC 3312 and NGC
3314a are moving towards us as part of a foreground substructure which has
already passed its pericenter and is on "out fall" from the cluster. The high
surviving HI content of the galaxies may suggest that the
substructure/intragroup medium can protect them from the harshest effects of
ram pressure, or that in fact the galaxies are on more tangential orbits.
