On Sunday, 31 December 2017 13:04:58 UTC, Norman Lynagh wrote:
These waves were videoed a few days ago at Cape Verde. It shows the
power of long-period waves even though the height is relatively modest.
I make the period something like 13-15 seconds

https://twitter.com/twitter/statuses/947449527065305088

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr

What helps as well is that, being volcanic islands, they slope steeply to the ocean floor. These waves are less likely to dissipate themselves than on a gentle slope.
I was there Easter 2013. Even on relatively quiet days the waves came ashore with quite a thump.