[Alleyfield]

We're talking about the baltic sea here. Its average depth is 55m.

Besides, it's already quite contaminated so there is a lot of environmental protection going around it.

http://upload.wikimedia.org/wikipedia/commons/e/eb/BalticSea...

As you can see, there really isn't places for the water to flow back and forth, so it's not a case of "the ocean is going to handle it"

Always consider the context.

[russss]

Yes, but it's still a massive body of water. Local heating of the water may be an environmental issue (although a small one, I think), but heating of the entire Baltic Sea is absolutely negligible.