Soo Lock
Sault Ste Maarie, MI

June 7, 2018

Map of Michigan Upper Peninsula
Official Army Corps of Engineers Soo Locks web site

Soo locks
Adapted from

The Soo Locks allow sailing vessels to travel between the lower Great Lakes to Lake Superior avoiding the 21 foot drop in the rapids in the St. Marys River. It is possible for ships to travel between Lake Superior and the Atlantic Ocean using these locks and the St Lawrence Seaway. However many vessels on the Great Lakes are too large for the locks on the Seaway. Iron ore mined near Dululth, Minnesota and shipped to smelters on the lower Great Lakes is the most common cargo in the locks.

The first locks on the Saint Marys River were built by the British in 1797 but were destroyed by the Americans during the war of 1812. Michigan had a lock built in 1855 so ship cargo would not need to be unloaded and portaged around the rapids. However it was soon considered too small for lake vessels and the Army Corps of Engineers took over the locks and opened a larger lock in 1881. An additional lock was built in 1896. But it soon was too small and additional locks were built. The current locks are:

A new lock to replace the Davis and Sabin locks has been authorized but construction has been delayed because it wasn't cost effective.

There is a smaller Canadian lock built in 1998 but is only 253 feet long, 51 feet wide and 44 feet deep. It is used for recreational and tour boats but all major shipping uses the larger U.S. locks.

Most Great Lake ship captains are certified to pilot ships through the locks. Ocean going ships are required to pick up a Great Lakes pilot while on the lakes.

There is no fee for ships using the locks although there a tax when ships are unload at lake ports that is used to help maintain the ports.

We visited on June 7 and observed a freighter and tour boats traversing the locks.

Preparing to enter

Two vessels are preparing to enter the locks from the Lake Superior level.

The freigher will enter the larger Poe Lock. It is the Canada Steamship Lines' CSL Assiniboine which was built in 1977. It 728 feet long and 26 feet wide and is smaller than many Great Lakes vessels. It is a shelf discharging bulk cargo carrier.

The largest vessel on the Great Lakes is 1014 feet long and 105 feet wide.

The small tour boat is turning around after being lifted to the Lake Superior level.

The tour ship can move more rapidly and has entered the MacArthur lock.

The freigher can be seen in the background ready to enter the Poe Lock.

Tour boat in lock
Freighter entering lock Tour boat going down

The freighter is almost in its lock but the tour boat has been lowered much of the way down.

freighter 1

The freighter is beginning to be lowered.

freighter 2
Freighter entering lock

Left: The tour boat is exiting the lock while another boat is waiting to enter.
Below: One sees lots of sea gulls but they are moving rapidly and its hard to get a good picture of them.

Sea gull

freighter 3

Above: The freighter is about ready to leave the lock. The second tour boat has entered the MacArthur Lock and it is tied to the side of lock.

Right: The freighter has begun exiting the lock. You can see the top of its deck but most of the hull is hidden.

freighter 4


Michigan UP map
Eastern portion of the Upper Peninsula.