  Over the last two decades, the Submillimetre Common-User Bolometer Array
(SCUBA) and SCUBA-2 on the James Clerk Maxwell Telescope (JCMT) achieved gread
success in discovering the population of dusty starburst galaxies in the early
universe. The SCUBA-2 surveys at 450 micron and 850 micron set important
constraints on the obscured star formation over cosmic time, and in combination
of deep optical and near-IR data, allows the study of protoclusters and
structure formation. However, the current submillimeter (submm) surveys by JCMT
are still limited by area of sky coverage (confusion limit mapping of only a
few deg^2), which prevent a systematic study of large samples of the obscured
galaxy population. In this white paper, we review the studies of the submm
galaxies with current submillimeter/millimeter (submm/mm) observations, and
discuss the important science with the new submm instruments in the next
decade. In particular, with a 10 times faster mapping speed of the new camera,
we will expect deep 850 micron surveys over 10 to 100 times larger sky area to
i) largely increase the sample size of submm detections toward the highest
redshift, ii) improve our knowledge of galaxy and structure formation in the
early universe.
