For a ferry that goes from one point to another with no stops in between, cars are loaded onto the ferry from one end, and en route, the cars face the direction of travel. When the ferry reaches the destination, the cars drive off. Easy peasy.
The ferry from Anacortes to Sidney makes a stop at Friday Harbor. This makes for some interesting logistics.
At Anacortes, cars are loaded from the rear,¹ and the cars destined for Friday Harbor are loaded first, so that they wind up at the front of the ferry.
When the ferry arrives at Friday Harbor, those cars exit from the front of the ferry.
And cars from Friday Harbor enter at the front of the ferry.
The ferry continues onward to Sidney, but things are interesting because you have cars on the deck which are facing directly at each other. The cars which boarded in Anacortes are in the back of the ferry facing forward, but the cars which boarded in Friday Harbor are in the front of the ferry facing backward. They are pointed at each other nose-to-nose.
We split up to find the answer.
But why don't you try to puzzle it out yourself. I'll wait.
One person asked the clerk at the gift shop, who said, "The wrong-way-facing cars back out."
Another person asked someone who was identified as an engineer, who said, "The wrong-way-facing cars make a three-point U-turn on the deck."
I asked somebody wearing a bright orange safety vest, figuring they worked on the car deck. "We leave one lane with all the cars pointing in the direction of travel and empty them first. We use that empty lane to unload the other cars pointed the same way. And the cars that are facing the wrong way make a big loop on the deck to turn around. We call that flipping."
I joked, "Maybe you could get a Lazy Susan to turn the cars around."
"Actually, that's what they do on some Alaska ferries."
Okay, so we asked three different people and got three different answers. Who's right?
Turns out everybody was right. (Though I was most right.)
The last vehicle to load at Friday Harbor was a large camper van, which blocked multiple lanes. They backed out off the ferry. They were closely followed by the cars in the lane where everybody was pointing the right way. (Like, no pressure on the camper van driver.)
The ferry crew then used that empty lane to get the other two lanes of forward-facing cars off the ferry.
Finally, the wrong-facing cars made U-turns to get off. Most of them used the open space on the deck to make a U-turn, but a few made three-point turns.
¹ The ferry is symmetric and doesn't really have a "front" or a "rear", but I gave them names based on the direction of travel.