The Herald had 459 passengers, 80 crew members, 81 cars, 47 cargo trucks and three other vehicles. The weather was good. The Herald passed the outer breakwater at 1824 and, about four minutes later, capsized.

The MS Herald of Free Enterprise disaster on March 6, 1987, remains one of the most rapid and tragic maritime accidents in modern history. After departing the Belgian port of Zeebrugge with its inner and outer bow doors still wide open, water flooded the car deck almost immediately, destroying the ship's stability due to the "Free Surface Effect." From the moment the water began pouring in to the point where the vessel capsized and settled on its side on a sandbar, the entire process took only 90 seconds. The high-speed nature of the capsizing meant there was virtually no time for the crew to launch lifeboats or for most passengers to escape the lower decks. Because the water was shallow, the ship did not fully submerge, but the speed of the event led to 193 fatalities. This incident resulted in high-fidelity changes to international maritime law, including the mandatory installation of "Bow Door Indicators" on bridges to ensure that officers have a visual confirmation that all doors are sealed before a vessel ever leaves its berth.