  The spectra of SN 2003dh, identified in the afterglow of GRB030329, are
modeled using radiation transport codes. It is shown that SN 2003dh had a high
explosion kinetic energy ($\sim 4 \times 10^{52}$ erg in spherical symmetry),
making it one of the most powerful hypernovae observed so far, and supporting
the case for association between hypernovae and Gamma Ray Bursts. However, the
light curve derived from fitting the spectra suggests that SN 2003dh was not as
bright as SN 1998bw, ejecting only $\sim 0.35\Msun$ of \Nifs. The spectra of SN
2003dh resemble those of SN 1998bw around maximum, but later they look more
like those of the less energetic hypernova SN 1997ef. The spectra and the
inferred light curve can be modeled adopting a density distribution similar to
that used for SN 1998bw at $ v > 25,000$\kms but more like that of SN 1997ef at
lower velocities. The mass of the ejecta is $\sim 8\Msun$, somewhat less than
in the other two hypernovae. The progenitor must have been a massive star ($M
\sim 35-40\Msun$), as for other hypernovae. The need to combine different
one-dimensional explosion models strongly indicates that SN 2003dh was an
asymmetric explosion.
