Important issues in stable, strongly-stratified flows, often occurring
in the atmosphere and oceans, are when and how `classical' 3D
turbulence appears, and the properties of the resulting turbulence.
In the oceans, at horizontal scales above a few meters, for example,
buoyancy often exerts a dominant influence on the flows, and hence how
turbulence is generated.  One pathway to classical 3D turbulence in a
strongly stratified flow is through the generation and breakdown of
propagating internal waves.  In this seminar another, a possibly more
general pathway is proposed, that of `stratified turbulence'; these
are motions at horizontal scales large enough to be dominated by
buoyancy.