Lake Huron is 21 feet lower than Lake Superior, which means that somehow the water must fall, tumble or otherwise be moved that distance. A series of rapids -- rapids that required boats to be portaged around them -- served that purpose until the Soo Locks were constructed in 1855.
How the locks work:
- A boat or ship enters the locks when the water is at its level -- the lock is at the high (filled) state if the boat comes from Lake Superior, and at the low state if from Lake Huron. If the lock is at the wrong state for the boat coming in, the Lock Master must fill or empty the lock.
- The gates behind the boat are closed forming a (relatively) water-tight enclosure.
- Openings in the gates that are hidden beneath the water are opened. If the boat is to be raised, the Superior-side gate is opened, and the water rushes in to fill the lock to the level of Superior. If the boat is to be lowered, the Huron-side is opened, and the higher water within the lock drains out, lowering the boat. Other than opening and closing the gates and the hidden drains, no pumps or other mechanical devices are needed.
- Once the boat is raised or lowered, the gate in front of the boat is opened, and it sails away.
We took a boat tour through the locks. Here are the pictures as we first traveled from Huron (lower) to Superior (higher). The first one is as we are entering the lock at the lowest water level, the second as we are floated higher, and the third as the gates are opening for us to enter Lake Superior:
On the way back, we entered the locks when the water was high, and descended as it was drained. The first is just as we are entering the lock, the second and third as we are descending, and the last is as the gates are opening for us to move into Lake Huron:
Now here's the promised Photo Caption Contest:
Just as we started to (very, very slowly) descend, I said to John, "Put your hands in the air like you're a daredevil on a roller coaster who refuses to hang on" -- and he did! I took the photo, but didn't count on the reaction of a bystander.
So what should the caption be? John suggested, "I hope I'm never this old!" Bragging rights only, but please give this photo the caption it deserves!