Sign as seen
To read the message in the reflection you need still water. Unfortunately, Albert had disturbed the water as we passed and I couldn't read it properly. I just got the gist, so I cheated by digitally reflecting the image.
Sign reflected to reveal the message
The message reads "THE REMAINS OF A WOODEN ICEBREAKER LIE SUBMERGED".
So why is the message there?
The answer lies on the web site of its creator, the artist Roger Palmer, which states:
A derelict landing stage on the Leeds & Liverpool Canal marks the site of Botany Bay in the Armley district of Leeds. Botany Bay received its name in 1808 as the landing place of the first shipment of Australian raw wool bound for Yorkshire mills.
Submerged in Botany Bay are the remains of a wooden icebreaker. These heavy vessels were pulled onto the ice by teams of horses and rocked from side to side, causing the ice to fracture. Wooden icebreakers were sunk in the summer months in order to preserve their timbers."
In a linked piece of art, which was displayed at the Leeds Gallery and is shown on his web site, Roger created The Remains (2007), a neon text illuminated in four phases:
The Remains of a Wooden Icebreaker
The Remains of a Wooden Icebreaker Lie Submerged
The Remains of a Wooden Icebreaker Lie Submerged in Botany Bay
So there is the answer. Thought provoking and informative. On Roger's site you can also see a better photograph of the sign and its reflection. You will also find a video of the reflection.
The sign has also been noted by one or two passing photographers.