Here is the rest of the story.
Just as I was going switch-stance for another Sw-Chachoo, I felt a strong smell of gasoline, and soon realised that I was sailing on pure diesel-oil. Even though it was nuking, there wasn't even a single ripple on the water. Scary shit.
I made my best efforts to get to shore without falling in, luckily I succeded. Then I alerted the dockers, who called the coast guard, who called the fire dept., who showed up unbelievably fast.
I had a talk with the coast guard; they asked me some questions, and I gave them some answers. We agreed on the fact that the oil must have been dumped - or leaked - from a shit passing through, which made me remember that I had seen an unusually large tanker outside the bay. The coast guard told me that they would do what they could to solve the case. I hope it worked out for them.
I didn't bring my camera, so unfortunately there are no pictures of the damage it caused. Just to give you a hint on how much oil there really was, I can say that the whole bay was covered. This is not good for the environment. Personally I think this is a big problem, not just because of the actual (hopefully temporary) damage, but also on account of the fact that the tankers that dock our harbors don't care about the waters they sail.
The diesel-oil is gone now, it probably evaporated, but the problem may not be so easy to solve next time. Next time it might be black oil.
We should take better care of our oceans.