What is the region of very calm seas and little to no wind on either side of the equator?

Doldrum is the region of very calm and little or no wind on either side of the equator. Doldrums which is also called convergence zone is an equatorial region of the Atlantic ocean which has sudden storms and light unppredictable winds. In addition doldrum is abelt around the earth near the equator where the sailing ships sometimes get stuck on windless water.