Satellite altimetry shows that daily mean significant wave heights (SWHs) and extreme SWHs have increased in the Southern Ocean, the South Atlantic, and the southern Indian Ocean over the last 2 decades. In winter in the North Atlantic, SWH has increased north of 45°N and decreased south of 45°N. SWHs likely to be exceeded every 100 years have also increased in the North Atlantic and the eastern tropical Pacific. However, this study also revealed the need for longer and more consistent series.