While we were in Seattle last Sunday we decided to stop at the Locks - the Hiram Chittenden Locks. Bonus round... it's a field trip!
We saw a full cycle of moving boats up and down through the locks. Lake Washington is about 20 feet above sea level... well, depends on the tide, I suppose, but it's a significant difference. We were amazed at the quantity of water and how quickly they managed to fill and empty the locks.
These first three pictures show the boats entering from the higher lake side. The green slime line on the wall shows the high-water mark.
In this second picture you can see the water level has dropped almost to it's lowest.
Then in this third picture, the boats are exiting the locks, heading out for Puget Sound.
There is also a fish ladder... we didn't get any good pics. Not many fish there, anyway. Most of the salmon came through more than a month ago. We saw just 4 or 5 Coho that were probably not the sharpest tacks in the box...
Not only were the locks themselves interesting, directly downstream is a train trestle that is a drawbridge. While we were there it had to be lowered for the Amtrak and then a freight train to pass, but raised for a tall ship to come through and enter the Locks. Very cool!