This is a great time for getting wet in the cause of art - taking your sketchbook and a watersoluble graphite pencil into the shallow surf on a safe beach and getting really close to those waves. You can create some lovely effects with a watersoluble pencil, and either brush over the sketch with a plastic aquash or water brush, or simply dip your finger in the sea and use that! The latter method, of course gives little scope for intricate detail, but that can be an advantage in stopping you fiddling.
This A5 sketch of boisterous surf on Marloes beach only took a few minutes and it shows the subtle tonal effects you can achieve with a watersoluble pencil. I worked round the small blobs of white foam, and I was especially keen to capture the interaction of hard and soft edges, many of which kept changing with the movement of the water. Even if you don't do a full painting from it, the sketch will teach you a lot about rendering wave action. One of the main advantages such a sketch has over a photograph is the dynamism and sense of movement you can portray with rapid and energetic hand movements.
So don't forget to take your sketchbook with you when you visit the seaside. There will always be something to catch your eye. I did quite a number of sketches that glorious June day at Marloes beach, some of which only took 3 or 4 minutes.