Looking for a submarine anime about twins

Back in the 2000s there was a show about a crew on a submarine trying to survive a war. The main guy was a blonde boy.

He had a twin brother that was in the enemy fleet and part of the empire equivalent. The only thing I recall about the show besides being a drama was that the trees floated in the water and had special properties that acted as radio waves.

I tried to look up submarine based anime and blonde twins and got nothing close on google.