The term SEA MOVEMENTS can be broken down into two crossword solutions, TIDES (5 letters) and WAVES (5 letters). Tides are the regular rise and fall of the sea level caused by the gravitational pull of the moon and sun. Tides occur twice a day and are affected by the shape of the coastline and the ocean floor. WAVES are the movement of energy through the ocean caused by wind, storms, and other factors. WAVES can travel thousands of miles across the ocean and can cause coastal erosion.