If you're only interested in protection then just get a protector filter, which will have the least impact on your images. UV, Skylight, Haze and Polarisers all change the UV light hitting your sensor (mainly changing the quality of blue light).
UV filters will remove that blue tinge you get in strong light, they are "clear" glass.
Skylight filters will warm an image, they have a pink coating to the glass.
Haze filters will again reduce blue tones but work well in dusty environments, they have a yellow coating.
Polarisers, while not as effective in reducing UV transmission, do reduce reflections, allowing for greater contrast.
These filters can be bought to allow different amounts of UV through and at different wavelengths, the uses of which entirely depend on the situations of the day.
So if you are looking to change your image at the time of capture, then I think a Polariser would suit your intended photography better. They are adjustable for the conditions and will provide greater definition between the sea and sky, while cutting reflection from the water.
However, if you find that haze really is an issue, which is quite possible at telephoto lengths and on a dusty beach, then a Haze filter will work better to get you clear images but with less contrast in the blues than a Polariser.
