/usr/share/eccodes/definitions/metar/seaState.table is in libeccodes-data 2.6.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | 0|Calm (glassy)|0
1|Calm (rippled)|0 – 0.1
2|Smooth (wavelets)|0.1 – 0.5
3|Slight|0.5 – 1.25
4|Moderate|1.25 – 2.5
5|Rough|2.5 – 4
6|Very|rough 4 – 6
7|High|6 – 9
8|Very high|9 –14
9|Phenomenal|Over 14
|