use RAW file mode as this will give you the most dynamic range to play with later, and the best quality photos
use a low ISO as this will also give the most dynamic range and the least noise, although it may mean longer shutter speeds which may become an issue if you don't want the waves to be blurry - you can't have your cake and eat it here as you need a small aperture too!
white balance is irrelevant if shooting RAW mode so don't waste precious time worrying about it - just set it to Auto, or for really rich red sunsets, to sunny day or flash.
consider setting exposure mode to manual, or aperture priority
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determine shutter speed by spot metering off the sky about 20-30deg from the position of the sun, or just use a trial and error approach to get the sky looking nice and saturated (a lazy way is just to use aperture priority and adjust exposure compensation to a negative value until it looks good - don't forget, your foreground subjects will be black silhouettes anyway)
if shutter speed is too slow to stop the water from looking sharp, you have several options:
increase ISO and/or open the aperture more
add a ND filter to make the shutter speed a LONG time such as 1-2 secs which will give the water a nice smoothed effect (best once the sun is below the horizon)