  We numerically study water wave packets on a spatially varying
counter-current in the presence of surface tension. Depending on the details of
the velocity profile, we show that traversable and bi-directional analogue
wormholes exist in fluid mechanics. The limitations on traversability of
wormholes in general relativity are absent here because of the dispersion of
water waves and the ability to form flow profiles that are not solutions of
Einstein's equations. We observe that negative energy can be trapped between
analogue horizons forming a LASER-like cavity. Six horizons are involved in the
trapping cavity because of the existence of two dispersive scales, in contrast
to previous treatments which considered two horizons and one dispersive scale.

Fluid Dynamics;General Relativity and Quantum Cosmology