Underneath the canal lies very murky waters though Venice officials get them maintained and cleaned on a regular basis.  This painting depicts the dark, murky waters of the canals.  I used my outliner hollow-container brushes to apply the outline of the paints then brushed in the other vivid colours with medium sized acrylic paintbrushes.  I love the contrast of the dark green depicting the algae, with the red depicting the rotting seaweed and the blue depicting the water.  The heavy texture depicts the movement in the water and the murkiness and heaviness of the body of water, full of debris and silt and all kinds of pollution.
If I could add that pungent smell of the canal to this painting, I would.