Going Through a Lock

The masts come down, the walls close in;
We almost scrape the sides.
The crewmen yell in Portuguese,
The hull's hard-working guides.

At most, an inch of space remains
Between the walls and ship.
The captain's likely bored, but it's
A highlight of my trip.

And then we're slowly rising
As the horn lets out a blast.
With masts in place, the light turns green;
We're through the lock at last.

We sail on down the river
Heading for the place we'll dock,
But I am glad I got to see
Our journey through the lock.