  The \textit{High resolution Coronal Imager (Hi-C)} has provided the sharpest
view of the EUV corona to date. In this paper we exploit its impressive
resolving power to provide the first analysis of the fine-scale structure of
moss in an active region. The data reveal that the moss is made up of a
collection of fine threads, that have widths with a mean and standard deviation
of $440\pm190$~km (Full Width Half Maximum). {The brightest moss emission is
located at the visible head of the fine-scale structure and the fine structure
appears to extend into the lower solar atmosphere.} The emission decreases
along the features implying the lower sections are most likely dominated by
cooler transition region plasma. These threads appear to be the cool, lower
legs of the hot loops. In addition, the increased resolution allows for the
first direct observation {of physical displacements of the moss fine-structure
in a direction transverse to its central axis. Some of these transverse
displacements demonstrate periodic behaviour, which we interpret as a signature
of kink (Alfv\'enic) waves. Measurements of the properties of the transverse
motions are made and the wave motions have} means and standard deviations of
$55\pm37$~km for the transverse displacement amplitude, $77\pm33$~s for the
period and $4.7\pm2.5$~km/s for the velocity amplitude. The presence of waves
in the transition region of hot loops could have important implications for the
heating of active regions.
