Sault Ste Marie, MI The St. Marys River is the only water connection between Lake Superior and the other Great Lakes. The water drops 21’ in a short ¾ mile long stretch. This rapids, or “sault”, made it impossible for trade vessels to pass. Vessels had to be unloaded and their contents portaged around. In 1797 the first lock on the St. Marys River was constructed to provide passage for trade canoes. Now about 10,000 ships pass through, some as long as 1,000 feet. The Soo Locks, Welland Canal and St. Lawrence Seaway provide an unbroken water connection between the Great Lakes and the Atlantic Ocean. However, boats larger than 740’ long and 78’ wide will not fit through the Welland Canal and can only travel between the 4 westernmost Great Lakes (Superior, Michigan, Huron and Erie). Gravity alone moves water in and out of the lock chambers. To lower the lock the filling valve is closed and the emptying valve is opened allowing water to flow out to the Lake Huron level. Once the vessel is secured inside the lock it takes 15-20 minutes to raise or lower the boat 21 feet (just over a foot a minute!) We, and many others, were mesmerized. We watched as a little tour boat came through and contrasted that to the 1,000’ ship Presque Isle in the next lock over. We also took a little time to appreciate the beauty around us as we explored a few area parks. A lot of the trees have changed into their fall plumage.