I don't think it is a good habit to tweak the white balance when you take the photograph. Take in RAW and then figure it out at your PC. By the time you tweak this and that, the moment has passed.
The other thing is... the sun has not set. If you waited a bit more, you will get this moon-like sun, which is redder and more glorious. It is difficult to meter properly if the sun is too bright. If you get the sea exposed nicely, the detail of the sun will inevitably be lost.
But I do like the effect of the sea. Maybe you should not take the sun at all, but focus on the sea? My brother took a nice picture of the sea once...
http://www.normanng.com/Main/PP6.htm
He's good, but I'm still crap but learning.
I'd appreciate it if someone can tell me the rough setting for taking a sunset handheld. I don't like to carry a tripod when I travel. Typically, if I were to open the aperture too wide, I will get this dark edges because the sun is much brighter compared to the surrounding. If I close the aperture too small, the shutter speed has to go down because there isn't much light at twilight. What is the largest I can open the aperture to get a decent sunset?