Video Transcription
Each of these 50-ton mules can tow more than 100 times its own weight.
And between them, they slowly inch the Zim into position.
With the Zim safely docked, the lockkeeper closes the gates to the Caribbean.
These massive gates are more than six feet thick and designed so that the weight of the water inside the lock will hold them closed.
Once shut, valves between the lock chamber and the lathe are opened and water floods into the lock.