A laboratory experiment was conducted to investigate the characteristics of turbulencegenerated by an internal wave ray breaking on a sloping bed. The width of the incident waveray was small compared to the bed length, so that an isolated turbulent patch was generatedby the breaking process, a configuration unique to the present study. The parameter rangecovered subcritical, critical and supercritical frequencies. Flow visualization and velocitymeasurements revealed that near critical conditions the flow was confined to a narrow regionabove the bed and, contrary to expectations, critical waves showed a weak turbulence field.Subcritical and supercritical reflection resembled wave–wave interaction between theincident and the reflected waves and showed comparable centred displacement lengthscales. Asthe incident waves became progressively supercritical instabilities were first initiatedaway from the bed. For supercritical waves the centred displacement lengthscale and theturbulent Reynolds number both increased steadily up to about γ≈2, after which they startedto decrease (γ=ω/ωc, where ω is the frequency of the incidentwave and ωc=Nsinβ is the critical frequency foran ambient uniform stratification of magnitude N and a bed angle of β). Forsubcritical waves an increase in the centred displacement lengthscale and the turbulentReynolds number was also observed. The mixed fluid generated at the boundary collapsed intothe fluid interior in the form of a horizontal two-dimensional viscous–buoyancy intrusion:the efficiency of mixing was, however, very small and no measurable change in the meandensity gradient was observed over the duration of the experiments.