THE Marchioness disaster took place in the early hours of 20 August 1989, but is still remembered to this day.
But what exactly happened to the historic vessels and how many lives did the tragedy claim? Here's what we know.
What happened to the boat?
On 20 August, 1989, the Thames riverboat sank after being struck by a dredger twice near Southwark in the early hours of the morning.
Marchioness had been hired for the evening for a birthday party and had about 131 people on board.
Both vessels were heading downstream, against the tide.
How many people lost their lives?
The disaster tragically claimed 51 lives.
It took 30 seconds for Marchioness to sink and 24 bodies were found within the ship when it was raised.
Coroner Dr Paul Knapman decided to cut the hands off more than 20 victims for identification purposes.
Safety concerns 30 years on
A public inquiry held in 2000 said poor lookouts on both vessels were responsible for the collision.
The Metropolitan Police were "ill-prepared" and had no plan for such an event, the inquiry found.
The inquiry made 30 river safety recommendations which were all accepted by John Prescott, the then deputy prime minister.
PLA chief executive Robin Mortimer said the tragedy led to a series of safety improvements on the Thames but the chances of an older vessel surviving a collision have not significantly improved.
He said: "There's a whole bunch of measures in place to reduce the likelihood of a collision occurring.
"The concern we've got is that the impact side of the risk is still fairly similar for older vessels because the vessel itself hasn't changed."
How is the Marchioness disaster remembered?
The 30th anniversary was remembered in a vigil next to the Thames last night.
The names of those who died were read aloud and petals were thrown into the water.
Survivors and families of the victims joined a procession from Southwark Cathedral to Bankside nearby the site of the accident, where a short service was held, reported Sky News.
Boats from the Royal National Lifeboat Institute, the fire and rescue service and Port of London Authority gathered on the river for the crews to pay their respects.