There are a few reasons why the waves at Boa vista are so big. First, the Cape Verde Islands are located in the middle of the Atlantic Ocean, which is a vast body of water with a lot of energy. This energy is transferred to the waves, causing them to grow larger as they travel toward shore.
Second, the coastline of Boa vista is rugged and mountainous, creating an ideal backdrop for large waves. The cliffs and headlands act as a natural funnel, amplifying the waves as they come crashing in.
Third, the trade winds that blow almost continuously from the east help to generate and sustain the waves. The winds create a consistent swell that travels across the ocean and breaks along the shores of Cape Verde.
Finally, the underwater geography of the area also plays a role in the formation of the waves. The seafloor around Boa Vista is very uneven, with deep underwater canyons and ridges. When waves encounter these features, they can become even larger.
The combination of these factors creates the big waves that are a signature of Boa Vista. These waves have been known to cause significant damage to property and infrastructure, but they also attract surfers from all over the world who come to ride them.