The seasonal sea level cycle has been investigated in the Caribbean Sea using altimetry and tide gauge time series from 27 stations and is characterized by large spatial variability. The coastal annual harmonic has amplitudes that range from 2 cm to 9 cm, peaking between August and October and semi‐annual harmonic with maximum amplitude of 6 cm, with most stations peaking in April and October. The coastal seasonal sea level cycle contributes significantly at most areas to sea level variability and can explain the sea level variance up to 78%. The barometric effect on the coastal sea level seasonal cycles is insignificant in the annual component but dominant at 9 stations in the semi‐annual cycle. The seasonal sea level cycle from 18 years of altimetry confirm the results obtained from the tide‐gauges and allow us to identify some dominant sea level forcing parameters in the annual and semi‐annual frequencies such as the Panama‐Colombia gyre driven by the wind stress curl and the Caribbean Low Level Jet modulating the sea level in the northern coast of South America and linked to the local upwelling. The seasonal sea level cycle in the Caribbean Sea is unsteady in time, with large variations in amplitude and phase lag at most of the stations, where the 5‐year amplitude in the coastal annual cycle can change over 6 cm in a 24 year period. The seasonal sea level cycle peaks about October when the probability of coastal impacts increases, especially in the northern coast of South America where the range is larger.