Douglas sea state scale
| Degree | Description | Wave height (m) |
|---|---|---|
| 0 | Calm (glassy) | 0 |
| 1 | Calm (rippled) | 0–0.10 |
| 2 | Smooth | 0.10–0.50 |
| 3 | Slight | 0.50–1.25 |
| 4 | Moderate | 1.25–2.50 |
| 5 | Rough | 2.50–4.00 |
| 6 | Very rough | 4.00–6.00 |
| 7 | High | 6.00–9.00 |
| 8 | Very high | 9.00–14.00 |
| 9 | Phenomenal | > 14.00 |