Cross sea

Cross seas have a large amount of directional spreading.

[1] This may occur when water waves from one weather system continue despite a shift in wind.

Waves generated by the new wind run at an angle to the old.

Until the older waves have dissipated, they can present a perilous sea hazard.

[3] Vessels fare better against large waves when sailing directly perpendicular to oncoming surf.

Cross swell at Île de Ré , France. The waves themselves are examples of cnoidal waves .
Cross sea near Lisbon , Portugal.