 During the riverboat's first official voyage, when the crowd moved to one side of the boat to view a passing scene of an Indian encampment or other sight, the boat would list from the side and water poured over the deck, as no one had determined "Mark Twain"s maximum safe passenger capacity.This oversight caused "Mark Twain" to almost capsize on a voyage a few days later when ride operators continued to wave more than 500 guests on board until the deck neared the water line.As the ship traversed the sparsely vegetated river route, it came loose from its track and got stuck in the muddy banks.