Where does it go? Because, if it is reflected back into the atmosphere, greenhouse gases would capture it and the air over the ocean would get warmer.
We know that that isn't the case and it's because sea water absorbs most of it. Which, in turn, causes evaporation and cools the sea surface and the air just above it.
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/sea/htg.rxml