The phrase "surface layer of the ocean" refers to the topmost part or the uppermost layer of water in the ocean that is closest to the air and receives sunlight. It is the part where many marine life and processes take place. Full definition
Now let's consider the thin surface layer of the oceans. (judithcurry.com)
And no, Rob, the thin surface layers of the oceans in non-polar regions are not warmed by direct solar radiation. (judithcurry.com)
«In response to the increase in greenhouse gas in the atmosphere, the positive temperature anomaly initially appears in the well - mixed surface layer of the ocean called the «mixed layer». (skepticalscience.com)