sea state refers to the general condition of the free surface on a large body of water, specifically with respect to wind waves and swell, at a certain location and moment. 

Here’s a breakdown of the World Meteorological Organization (WMO) sea state code, which provides a concise description of sea conditions:

1. Calm (glassy): Wave height is 0 meters (glassy surface).
2. Calm (rippled): Wave height ranges from 0 to 0.1 meters (small ripples).
3. Smooth (wavelets): Wave height is between 0.1 and 0.5 meters (gentle wavelets).
4. Slight: Wave height varies from 0.5 to 1.25 meters.
5. Moderate: Wave height ranges from 1.25 to 2.5 meters.
6. Rough: Wave height is between 2.5 and 4 meters.
7. Very rough: Wave height spans 4 to 6 meters.
8. High: Wave height extends from 6 to 9 meters.
9. Very high: Wave height reaches 9 to 14 meters.
10. Phenomenal: Wave height exceeds 14 meters.

Additionally, sea states are often characterized by the direction from which the swell is coming, which should be recorded. In marine engineering, two key parameters are used: the significant wave height (H1/3)—the mean wave height of the highest third of the waves—and the mean wave period (T1).

Remember that sea conditions can change rapidly, so mariners and ship designers closely monitor sea states to ensure safety and efficient operations.