The landforms like beaches, sand bar, lagoons are formed due to depositional work of the sea waves. 

(i) Beach:

• Large amount of sediments come from the landward side in areas between two adjoining headlands. 
• Moreover, as these areas are shallow, the velocity of the waves decreases.
• As a result, the sediments that come from the land, as well as those coming from the deep sea, get deposited in this area.
• Predominantly fine sand gets settled along the coast. 
• Such sandy deposits along the coasts are called beaches.

(ii) Lagoon:

• The brackish water separated from the seawater by sand bars and lying in the areas between the coast and bars is called a lagoon. 
• As the waters are separated from the open sea, large waves are not generated. 
• These lagoons run parallel to the sea coast.

(iii) Sand bars:

• Sand gets deposited along the sides of the headlands.
• The deposition extends parallel to the coast from one headland to the next. 
• Over a period of time, these deposits extend over long distances forming bars that protrude into the water at some distance away from the beach. 
• These are known as ‘sand bars’, Sometimes, the eroded material from the’ beach, gives rise to the sand bars.