  We review published deep surveys in the submillimeter (sub-mm) regime from
the new Sub-millimetre Common User Bolometer Array (SCUBA) on the 15-m James
Clerk Maxwell Telescope (JCMT), Mauna Kea, Hawaii. Summarising the number
counts of faint sub-mm sources determined from the different surveys we show
that the deepest counts from our completed SCUBA Lens Survey, down to 0.5mJy at
850um fully account for the far-infrared background (FIRB) detected by COBE. We
conclude that a population of distant, dust-enshrouded ultraluminous infrared
galaxies dominate the FIRB emission around 1mm. We go on to discuss the nature
of this population, starting with the identification of their optical
counterparts, where we highlight the important role of deep VLA radio
observations in this process. Taking advantage of the extensive archival Hubble
Space Telescope (HST) observations of our fields, we then investigate the
morphological nature of the sub-mm galaxy population and show that a large
fraction exhibit disturbed or interacting morphologies. By employing existing
broadband photometry, we derive crude redshift limits for a complete sample of
faint sub-mm galaxies indicating that the majority lie at z<5, with at most 20%
at higher redshifts. We compare these limits to the initial spectroscopic
results from various sub-mm samples. Finally we discuss the nature of the
sub-mm population, its relationship to other classes of high-redshift galaxies
and its future role in our understanding of the formation of massive galaxies.
