  We present ongoing investigations of maximally supersymmetric Yang--Mills ($Q
= 16$ SYM) theory in three space-time dimensions. At low temperatures and large
$N$ this theory is related to black branes in higher-dimensional quantum
gravity. Building on previous work that focused on the homogeneous `D2' phase
of the theory, we are now exploring phase transitions between this D2 phase and
the localized `D0' phase.
