easy! 1000+++tonns amd 11-15 knots in a long-shallow area... but my main problem is to understand how they managed to miss the pier by 400 meters!
Here you have a picture of the area of the ferry ran aground.
the top blue marker shows the direction the ferry comes from.
the lower blue marker on the left shows where the ferry pier is.
the blue marker on the right shows where it ran aground (470m)