  We use experiments to study the evolution of bubble clusters in a swarm of
freely rising, deformable bubbles. A new machine learning-aided algorithm
allows us to identify and track bubbles in clusters and measure the cluster
lifetimes. The results indicate that contamination in the carrier liquid can
enhance the formation of bubble clusters and prolong the cluster lifetimes. The
mean bubble rise velocities conditioned on the bubble cluster size are also
explored, and we find a positive correlation between the cluster size and the
rise speed of the bubbles in the cluster, with clustered bubbles rising up to
$20\%$ faster than unclustered bubbles.
