  Superfluid Turbulence is unusual and presents a challenge to fluid
dynamicists because it consists of two coupled, inter penetrating turbulent
fluids: the first is inviscid with quantised vorticity, the second is viscous
with continuous vorticity. Despite this double nature, the observed spectra of
the superfluid turbulent velocity at sufficiently large length scales are
similar to those o ordinary turbulence. We present experimental, numerical and
theoretical results which explain these similarities, and illustrate the limits
of our present understanding of superfluid turbulence at smaller scales.
