Calm sea

A calm sea is a marine condition in which the water surface is smooth or glassy, with little to no wind-driven wave activity and negligible wave height. It usually occurs in very light winds, sheltered waters, or under stable high-pressure weather, but it does not necessarily mean there is no swell, current, or vessel wake.

For boaters, calm seas can make berthing, anchoring, tender transfers, fishing, and passenger comfort easier, but they can also reduce sailing performance and steerage if there is insufficient wind. Passage planning should still consider Sea State, Wave Height, and Tidal Current, as smooth water can quickly become uncomfortable where current, swell, or a new breeze develops.

PredictWind forecasts help identify likely calm sea windows using wind, wave, gust, and model data in the Forecast and Offshore Apps. For coastal or offshore trips, compare models and use Weather Routing or Departure Planning to confirm whether calm conditions are expected along the whole route, not just at departure.