  We report the low-temperature properties of SrNd$_2$O$_4$, a geometrically
frustrated magnet. Magnetisation and heat capacity measurements performed on
polycrystalline samples indicate the appearance of a magnetically ordered state
at $T_{\rm N}=2.28(4)$~K. Powder neutron diffraction measurements reveal that
an \afm\ state with the propagation vector \QV\ is stabilised below this
temperature. The magnetic order is incomplete, as only one of the two Nd$^{3+}$
sites carries a significant magnetic moment while the other site remains
largely disordered. The presence of a disordered magnetic component below
$T_{\rm N}$ is confirmed with polarised neutron diffraction measurements. In an
applied magnetic field, the bulk properties measurements indicate a phase
transition at about 30~kOe. We construct a tentative $H$-$T$ phase diagram of
\sno\ from these measurements.
