  The goal of helioseismology is to provide accurate information about the
Sun's interior from the observations of the wave field at its surface. In the
last three decades, both global and local helioseismology studies have made
significant advances and breakthroughs in solar physics. However, 3-d mapping
of the structure and dynamics of sunspots and active regions below the surface
has been a challenging task and are among the longest standing and intriguing
puzzles of solar physics due to the complexity of the turbulent and dynamic
nature of sunspots. Thus the key problems that need to be addressed during the
next decade are: (i) Understanding the wave excitation mechanisms in the quiet
Sun and magnetic regions, (ii) Characterizing the wave propagation and
transformation in strong and inclined magnetic field regions and understanding
the magnetic portals in the chromosphere, (iii) Improving helioseismology
techniques and investigating the whole life cycle of active regions, from
magnetic flux emergence to dissipation, and (iv) Detecting helioseismic
signature of the magnetic flux of active regions before it becomes visible on
the surface so as to provide warnings several days before the emergence. For a
transformative progress on these problems require full disk, simultaneous
Doppler and vector magnetic field measurements of the photosphere up to the
chromosphere with a spatial resolution of about 2 arc-sec as well as
large-scale radiative MHD simulations of the plasma dynamics from the
sub-photosphere to the chromosphere.
