Photograph your favourite beach or catch the movement of the waves or changing of the tides. Your imagination is the limit, as long as the ocean is included.
So many questions to think about.
Most articles that I read about photographing seascapes mentioned two pieces of gear to consider other than your camera. Most often mentioned was using a tripod and the second piece of gear was the use of neutral density filters to help control the amount of light.
Suggestions for taking a fantastic seascape starts with making a plan. Find a location that you what to capture. Is this image going to be an expansive scene or an intimate scene? What elements do you want in the foreground? What elements do you want in the background? What angle do you want? Where is the source of light coming from?
Are you going to shoot during the golden hour or the blue hour? Both times can create a magical atmosphere and your location determines which one you might want to use.
Be aware of the tides for the water level as high tide may cover the foreground that you wanted or low tide may expose too much foreground or background. Tide may also affect water movement and wave size.
Do you want to blur the water or freeze it? Do you want to keep the background sharp or the whole image sharp? Or do you want to use In Camera Movement for an abstract or artistic image?
Will your image be in colour or black and white?
The weather will help with emotion in the image. Will the image be soft and serene or will there be dramatic stormy skies. Don’t leave this theme assignment until the last minute!
A link to a great article on photographing seascapes: https://www.capturelandscapes.