Bimodal and crossing seas can generate extreme and freak wave events (see e.g. Tamura et al., 2009). Sea states comprised of swell and wind waves resulting in two distinctive frequency peaks are a common feature in oceans. If they travel along different directions, two distinctive directional peaks can be detected. These are referred to here as bimodal or crossing seas. This bimodal state can also be caused by rapidly turning wind, which will result in two sea states with similar frequency distributions and different directions. This chapter summarises the mechanisms responsible for formation of rogues waves in crossing seas, laboratory measurements, numerical simulations of crossing wave fields and nonlinear wave statistics.