Infragravity wave
![Classification of the spectrum of ocean waves according to wave period.[1]](/uploads/202501/20/Munk_ICCE_1950_Fig1.svg1725.png)


Infragravity waves are surface gravity waves with frequencies lower than the wind waves – consisting of both wind sea and swell – thus corresponding with the part of the wave spectrum lower than the frequencies directly generated by forcing through the wind.