  Epsilon-near-zero (ENZ) media disclose the peculiarities of electrodynamics
in the limit of infinite wavelength but non-zero frequency for experiments and
applications. Theory suggests that wave interaction with obstacles and
disturbances dramatically changes in this domain. To investigate the optics of
those effects we fabricated a nanostructured 2D optical ENZ multilayer
waveguide that is probed with wavelength-tuned laser light via a nanoscale wave
launch configuration. In this experimental framework we directly optically
measure wave propagation and diffraction in a realistic system with the level
and scale of imperfection that is typical in nanooptics. As we scan the
wavelength from 1.0 $\mu$m to 1.7 $\mu$m, we approach the ENZ regime, and
observe the interference pattern of a micro-scale Young's double slit to
steeply diverge. By evaluating multiple diffraction orders we experimentally
determine the effective refractive index $n_{eff}$ and its zero-crossing as an
intrinsic measured reference, which is in agreement with theoretical
predictions. We further verify that the double-slit and specifically placed
scattering objects become gradually invisible when approaching the ENZ regime.
We also observe that light-matter-interaction intensifies towards ENZ and
quantify how speckle noise, caused by tiny random imperfections, increasingly
dominates the optical response and blue-shifts the cut-off frequency.
