Constructive waves build beaches. Each wave is low. As the wave breaks it carries material up the beach in its swash. The beach material will then be deposited as the backwash soaks into the sand or slowly drains away. These waves are most common in summer than in winter. They are typically found in sheltered bays and spits where they build up sandy beaches.
Constructive waves have a long wavelength and a low-frequency (8– 10 waves per minute). They have a low wave height (typically under 1 metre). The wavefront is gently sloping and gains a little height, breaks and spills onto the beach. Water spreads a long way up the gently sloping beach.
The video below shows constructive waves at Mappleton, Holderness Coast.