  We report direct observations of surface waves from a stereo camera system
along with concurrent measurements of wind speed during an expedition across
the Southern Ocean in the austral winter aboard South African icebreaker
S.A.~Agulhas~II. Records include water surface elevation across a range of wave
conditions, spanning from early stages of wave growth to full development. We
give experimental evidence of rogue seas, i.e., sea states characterizided by
heavy tails of the probability density function well beyond the expectation
based on bound mode theory. These conditions emerge during wave growth, where
strong wind forcing and high nonlinearity drive wave dynamics. Quasi-resonance
wave-wave interactions, which are known to sustain the generation of large
amplitude rogue waves, capture this behaviour. Wave statistics return to
normality as the wind forcing ceases and waves switch to a full developed
condition.
