Here in Buenos Aires we removed a lot of sunk ships from https://en.wikipedia.org/wiki/Matanza_River (a small river on the side of the city, not the huge main river) to increase water flow and try to reduce the huuuuuuuge contamination.

Good idea. You should do that.

Shouldn't be too hard, just detonate all the explosives they're loaded with and then go around picking up all the pieces.