  We investigate self-dualities in three-dimensional $\mathcal{N}=2$
supersymmetric gauge theories. The electric and magnetic theories share the
same gauge group. The examples include $SU(2N)$, $SO(7)$ and $SO(8)$ with
various matter contents. The duality exchanges the role of the baryon and
Coulomb branch operators in some examples. In other examples, the Coulomb
branch operator becomes an elementary field on the dual side. These
self-dualities in turn teach us a correct quantum structure of the Coulomb
moduli space of vacua. Some dualities show symmetry enhancement.
