How can you cruise only half the Panama Canal?

Cruising down the Panama Canal has to be on the bucket list of every serious cruiser out there, normaly from Fort Lauderdale to L.A or vice versa.
For people who either don't want to or just don't have the time most cruise lines also offer the option of only cruising half the canal so you can say you can experience it without it taking up a good chucnk of your holiday.
But here's a question for you. In a great big cruise ship, how do you cruise only half a canal, it's not like you can turn around half way through?
Is it?
Well actually that's exactly what you do.
The canal itself, a man made construction finished in 1914 is actualy a set of three interconnecting lakes -
The Miraflores lake,
The Pedro Miguel lake and the
Gatun lake.

The three lakes, with the Gatun lake being closest to the Atlantic, are connected by a seiries of locks of the same name enabling ships to pass through.

Whenever you see a cruise line advertising a partial transit cruise through the Panama canal what will happen is that you'll cruise up the Panama canal to Gatun lake where the cruise ship will then turn around and exit the canal by the same point.

Happy cruising