  Quantum limit is quite easy to achieve once the band crossing exists exactly
at the Fermi level ($E_F$) in topological semimetals. In multilayered Dirac
fermion system, the density of Dirac fermions on the zeroth Landau levels (LLs)
increases in proportion to the magnetic field, resulting in intriguing angle-
and field-dependent interlayer tunneling conductivity near the quantum limit.
BaGa$_2$ is an example of multilayered Dirac semimetal with anisotropic Dirac
cone close to $E_F$, providing a good platform to study its interlayer
transport properties. In this paper, we report the negative interlayer
magnetoresistance (NIMR, I//c and B//c) induced by the tunneling of Dirac
fermions on the zeroth LLs of neighbouring Ga layers in BaGa$_2$. When the
field deviates from the c-axis, the interlayer resistivity $\rho_{zz}(\theta)$
increases and finally results in a peak with the field perpendicular to the
c-axis. These unusual interlayer transport properties (NIMR and resistivity
peak with B$\perp$c) are observed together for the first time in Dirac
semimetal under ambient pressure and are well explained by the model of
tunneling between Dirac fermions in the quantum limit.
