[Gazza711]

As per OS. Sun is in the clouds and clearly shows sea beyond the horizon at the same level.

[Bobby Shafto]

I think your picture shows a surface layer of cloud/mist/haze that's obscured the actual horizon creating an apparent horizon. The reflected sunlight is showing through it. It's not "sea beyond the horizon." It's showing where the actual horizon is (or may be, depending on temperature inversions.)

Cool picture though.