  The potential of future high statistics atmospheric neutrino experiments is
considered, having in mind currently discussed huge detectors of various
technologies (water Cerekov, magnetized iron, liquid Argon). I focus on the
possibility to use atmospheric data to determine the octant of $\theta_{23}$
and the neutrino mass hierarchy. The sensitivity to the $\theta_{23}$-octant of
atmospheric neutrinos is competitive (or even superior) to long-baseline
experiments. I discuss the ideal properties of a fictitious atmospheric
neutrino detector to determine the neutrino mass hierarchy.
