Close your eyes and listen to the sound of the sea. The slow, churning, white noise of the ocean can be comforting. Is the sound loud or quiet? Does the sea sound calm or choppy?
Hear the waves breaking and dispersing on the beach. Listen to the different sound the waves make as they retreat again, drawing sand or pebbles back down the beach with them. Is the frequency of the waves regular or irregular? Listen for a while to see whether you can hear if any waves are bigger than others.
It is often breezy at the coast, sometimes positively windy. Listen to the sound of the wind swishing around and making a rustling sound. Is the wind blowing consistently or in gusts?