The Sun is a most remarkable object: it is filled with vibrantly evolv- ing magnetic fields, well-mixed hierarchically-arranged turbulent con- vective cells, and also poorly-mixed sunspots that persist with im- punity. Solar variability has direct consequences for the earth and space weather, an important reason to develop an appreciation for the physics of the solar cycle (dynamo).

Direct observation of the solar subsurface is impossible due to the high degree of optical scattering by the partially ionized plasma that inhabits the near-surface layers of the Sun. The deepest part of the Sun visible to us, known as the photosphere (also the solar surface), appears as a roiling, turbulent, radiative, magnetized, convecting plasma. At first glance, it would seem therefore that subtle ques- tions relating to the subsurface constitution of the Sun seem com- pletely unanswerable and the interior properties unknowable. How- ever, analogous to geoseismology, a great deal can be gleaned about the internal structure and dynamics of the Sun by carefully observ- ing and analyzing the surface wavefield. This has been made possible over the last few decades through the development and application of techniques of helioseismology.

In this talk I will outline some of the major results in this area over the last two decades and discuss some recent developments pertaining to the properties of turbulence in the deep-convection zone of the Sun.