  The origin of the ultrahigh-energy (UHE) cosmic rays (CRs) from the second
knee ($\sim6\times10^{17}$eV) above in the CR spectrum is still unknown.
Recently, there has been growing evidence that a peculiar type of supernovae,
called hypernovae, are associated with sub-energetic gamma-ray bursts (GRBs),
such as SN1998bw/GRB980425 and SN2003lw/GRB031203. Such hypernovae appear to
have high (up to mildly relativistic) velocity ejecta, which may be linked to
the sub-energetic GRBs. Assuming a continuous distribution of the kinetic
energy of the hypernova ejecta as a function of its velocity $E_k\propto
(\Gamma\beta)^{-\alpha}$ with $\alpha\sim 2$, we find that 1) the external
shock wave produced by the high velocity ejecta of a hypernova can accelerate
protons up to energies as high as $10^{19} {\rm eV}$; 2) the cosmological
hypernova rate is sufficient to account for the energy flux above the second
knee; and 3) the steeper spectrum of CRs at these energies can arise in these
sources. In addition, hypernovae would also give rise to a faint diffuse UHE
neutrino flux, due to $p\gamma$ interactions of the UHE CRs with hypernova
optical-UV photons.
