A boat that normally carries visitors across the Knysna estuary partially capsized on Friday.
"The accident happened during the early hours of this morning. No one was on board and no one was hurt," said the Featherbed Company in a statement.
Officials are working to find the cause of the incident.
The vessel, named the Paddle Cruiser, takes guests on lunch and dinner cruises through the lagoon throughout the year. It is believed to be South Africa's only paddle-driven large vessel.
According to Martin Hatchuel, a horticulturist at Featherbed who was at the scene, the incident was unprecedented. "We have every possible safety measure in place, so it's new ground for all of us," he said.
Hatchuel praised the efforts of local officials and volunteers who were working to right the ship.