  We study the spontaneous emergence of three-dimensional motion from a
quiescent, pure conduction state in stably stratified, convective flow within a
triangular enclosure, which eventually self-organizes into a two-dimensional
steady state. This phenomenon demonstrates that the optimal disturbance path to
reach the final state is more complex than the state itself, indicating the
"fastest" route involves a higher-dimensional intermediate state. This provides
a model for transient spatio-temporal chaos in nonlinear dynamical systems and
a challenge for classical hydrodynamic stability theory.
