Duckboards are underwater tow boards. Pioneered by an unknown person(s) perhaps centuries ago our duck-boarding was championed by the McEwen family on Lake of the Woods.  Our families grew up together on Whitefish Bay of Lake of the Woods duck-boarding, diving acrobatically and looking at underwater life. The tow board acts very much like a deep-water  fishing bait with a plastic spoon on the front, when pointed down you shoot downwards and when your breath runs out you point it up and you pop to the surface. It gives the sensation of flying and is enjoyed by all age groups because it is a low impact, slow speed but high reward experience. 
WARNING  Duckboards are meant to be used in bodies of water where visibility and water quality is excellent.  Diving to deep without equalization can cause ear damage.