  We study asymptotic symmetry algebras for classes of three dimensional
supergravities with and without cosmological constant. In the first part we
generalise some of the non-Dirichlet boundary conditions of $AdS_3$ gravity to
extended supergravity theories, and compute their asymptotic symmetries. In
particular, we show that the boundary conditions proposed to holographically
describe the chiral induced gravity and Liouville gravity do admit extension to
the supergravity contexts with appropriate superalgebras as their asymptotic
symmetry algebras. In the second part we consider generalisation of the 3d
$BMS$ computation to extended supergravities without cosmological constant, and
show that their asymptotic symmetry algebras provide examples of nonlinear
extended superalgebras containing the $BMS_3$ algebra.
