I would say that drawing realistically with pencil is one of the most challenging forms of art. You are working with a medium that doesn’t cover as quickly as say a painting medium. To depict things such as beaches and seascapes requires a great deal of patience, especially when working in realism. I hope the following videos and links will assist you in learning how to draw a realistic beach with your pencil medium.
How to Draw a Beach: Pencil Drawing Step by Step
How to Draw A Realistic Rocky Beach Scene
How TO Draw Scenery OF Seascape Sketch Step By Step/Draw a beautiful Scenery With Pencil
How to Draw a Lighthouse, the Sea and Sky