Mr. Hopkins announced the first gator sighting — a small one in the water with only its snout above the surface. Crew members hurried to the port side of the decks to get a glimpse. James Arnpriester, a bearded young captain, declared: “That’s it for me. That’s all I wanted to see on this trip.”

But a few minutes later, they spotted a much larger gator slinking off the left bank as the ferry’s low wake approached. Almost immediately, the ferry ceased gliding through the canal. The pontoon on the right — or starboard — side of its hull had sliced into a mound of mud on the bottom that pulled the boat toward the right bank.

The captain cut the engines. The electronic instruments indicated that the water should have been deep enough to pass through, but the boat was clearly stuck. The mood onboard shifted from calm to perturbed.

Maneuvering out of the muck could have been easy, but Mr. Caspers was concerned about doing any damage to the hull or propellers of a brand new boat that cost close to $4 million. He called a towing company but learned that it could offer no help anytime soon. Then he called all hands to the top deck to explain that they might be spending the night right there, several feet from shore in a canal that they knew contained at least two gators.

The captain listed the options: Wait for a tow; try to lighten the ferry by dumping a tank of 200 gallons of potable water and hope to float off; or start up the engine on the port side, which was still floating, and use it to turn the boat clockwise until it was safe to start the starboard engine.