  The 3D-Drift And SHift (3D-DASH) program is a \textit{Hubble Space Telescope}
WFC3 F160W imaging and G141 grism survey of the equatorial COSMOS field.
3D-DASH extends the legacy of HST near-infrared imaging and spectroscopy to
degree-scale swaths of the sky, enabling the identification and study of
distant galaxies ($z>2$) that are rare or in short-lived phases of galaxy
evolution at rest-frame optical wavelengths. Furthermore, when combined with
existing ACS/F814W imaging, the program facilitates spatially-resolved studies
of the stellar populations and dust content of intermediate-redshift
($0.5<z<2$) galaxies. Here we present the reduced F160W imaging mosaic
available to the community. Observed with the efficient DASH technique, the
mosaic comprises 1256 individual WFC3 pointings, corresponding to an area of
1.35 deg$^2$ (1.43 deg$^2$ in 1912 when including archival data). The median
$5\sigma$ point-source limit in $H_{160}$ is 24.74 mag. We also provide tools
to determine the local point spread function (PSF), create cutouts, and explore
the image at any location within the 3D-DASH footprint. 3D-DASH is the widest
\textit{HST}/WFC3 imaging survey in the F160W filter to date, increasing the
existing extragalactic survey area in the near-infrared at HST resolution by an
order of magnitude.
