Ocean Seagulls Screensaver shows a huge rock in the middle of the ocean with a seagull standing on it. The image is very pleasant, which combined with the sounds of seagulls and the ocean, and the movement of the water, creates a very realistic and relaxing atmosphere. Unfortunately, the screensaver doesn't include music and neither can you add your own, but I think this was done intentionally, so you could concentrate on the nature sounds only.
Sadly, the screensaver doesn't offer many customization options. You will be able to select the image size (proportional or stretch) and animation speed of the water. The settings menu includes a small viewer that allows you to view the screensaver's image as you configure it. Moreover, if you check the "Auto preview" option, the image will be shown even with effects, just like in the screensaver. Optionally, you can add a transparent analog clock in any of the screen corners.
In short, if you are looking for a nice and pleasant screensaver to decorate your screen with, Ocean Seagulls Screensaver can be an excellent choice.