An old frozen rusty ship matte painting.  I followed the Youtube tutorial here.

For the skyline, I used this photo I took of the Miami skyline during a family cruise to the Bahamas a couple years ago.

Other photos used from a free photo stock site:

I began by making a sketch.

Then, I layered the photos.

Adjusted the colors, masked textures onto the ship, painted the snow all the way to the skyline, and painted snow on the buildings as well as on the ship.

Added filters.

Added snow.

Close up of completed ship.