I've got some friends who are part of this organisation:

http://www.sas.org.uk/

I didn't think we still dumped raw sewage in the sea anymore. That's quite a horrifying story.

I was once snorkling off Corfu and found myself following a long pipe on the seabed - I became aware of something blurred in the distance, ahead of me. Some sort of large mass - near the surface. On getting closer I found it to be the end of the pipe, a section where it wasn't weighed down to the bed. There was a huge mouldy growth of fungus or something feeding on the open end where all manner of human biproduct was spewing into the water that I was swimming in! I swam as fast as I could back to the beach. Gahhh, just typing this and remembering it makes me want to puke.