The word "horsepower" today describes the output of engines, electric motors and other machinery, but naturalist Mark Fraser takes us back to the word's more literal meaning, when horses really did power many human machines and activities.

One such activity was boating. 

"Imagine a world where horses actually powered a huge ferry 63-feet-long

crossing a giant lake, such as Lake Champlain, at speeds faster then 6

knots," says Mark. "There was a time, long ago, when that was actually very common."

(Image: François Marchal)

He explains that, for many of these operations, two horses walked on a giant turn-table wheel that propelled early American "team boats." The wheel "moved a gear connected to two large paddle wheels located on the rear quarters of the ship not far from

the stern."

Mark continues, "Horse powered ferries like the one sunk in the Bay of

Burlington, Vermont, had reached their heyday in the 1830's and 40's. Eventually, in the 1850's, the steam boat took over and the days of horse

powered ferries quickly came to an end."

Watch as Mark dives into Lake Champlain to explore the sunken remains of one of these historic horse-powered ferries that has since become the home for numerous fresh water species, such as yellow perch, sponges, and mussels.