  The purpose of this paper is to extend the store of models able to support
integrable defects by investigating the two-dimensional Boussinesq nonlinear
wave equation. As has been previously noted in many examples, insisting that a
defect contributes to energy and momentum to ensure their conservation, despite
the presence of discontinuities and the explicit breaking of translation
invariance, leads to sewing conditions relating the two fields and their
derivatives on either side of the defect. The manner in which several types of
soliton solutions to the Boussinesq equation are affected by the defect is
explored and reveals new effects that have not been observed in other
integrable systems, such as the possibility of a soliton reflecting from a
defect or of a defect decaying into one or two solitons.
