Over the last decade our understanding of the high redshift universe
has been transformed by studies of Lyman break galaxies - rest-frame
ultraviolet luminous starbursting galaxies at z>2. More recently this
work has been expanded to study galaxies at z>5, and samples of such
sources are now giving a coherent picture of the locations and density
of unobscured star formation within 1-2 Gyrs of the Big Bang. However,
while this work is adding greatly to our understanding of early galaxy
formation, it remains an incomplete picture. Much of the material in
the early universe is ultraviolet-dark, and hence inaccessible to
Lyman break galaxy surveys which operate in the observed-frame
optical. We have recently been expanding our extensive work on Lyman
breaks to explore the ultraviolet-dark material in their environs,
using infrared data from Spitzer, sub-millimetre data from MAMBO and
LABOCA and millimetre data from the GBT and ATCA. I will present my
recent work on z>5 fields, discussing the use of optical data as a
pointer towards large scale structure in the early universe and
implications for studies with ALMA and other new instrumentation.