  We present an overview and the first data release of ZFIRE, a spectroscopic
redshift survey of star-forming galaxies that utilizes the MOSFIRE instrument
on Keck-I to study galaxy properties in rich environments at $1.5<z<2.5$. ZFIRE
measures accurate spectroscopic redshifts and basic galaxy properties derived
from multiple emission lines. The galaxies are selected from a stellar mass
limited sample based on deep near infra-red imaging ($\mathrm{K_{AB}<25}$) and
precise photometric redshifts from the ZFOURGE and UKIDSS surveys as well as
grism redshifts from 3DHST. Between 2013--2015 ZFIRE has observed the COSMOS
and UDS legacy fields over 13 nights and has obtained 211 galaxy redshifts over
$1.57<z<2.66$ from a combination of nebular emission lines (such as \Halpha,
\NII, \Hbeta, \OII, \OIII, \SII) observed at 1--2\micron. Based on our
medium-band NIR photometry, we are able to spectrophotometrically flux
calibrate our spectra to \around10\% accuracy. ZFIRE reaches $5\sigma$ emission
line flux limits of \around$\mathrm{3\times10^{-18}~erg/s/cm^2}$ with a
resolving power of $R=3500$ and reaches masses down to \around10$^{9}$\msol. We
confirm that the primary input survey, ZFOURGE, has produced photometric
redshifts for star-forming galaxies (including highly attenuated ones) accurate
to $\Delta z/(1+z\mathrm{_{spec})}=0.015$ with $0.7\%$ outliers. We measure a
slight redshift bias of $<0.001$, and we note that the redshift bias tends to
be larger at higher masses. We also examine the role of redshift on the
derivation of rest-frame colours and stellar population parameters from SED
fitting techniques. The ZFIRE survey extends spectroscopically-confirmed $z\sim
2$ samples across a richer range of environments, here we make available the
first public release of the data for use by the
community.\footnote{\url{http://zfire.swinburne.edu.au}}
