Prayers were said for the 51 people who died in the Marchioness riverboat disaster on Thursday, the 20th anniversary of the sinking of the Thames pleasureboat near Southwark Bridge.
The Marchioness, which was carrying 130 people, was hit by the dredger Bowbelle near Cannon Street railway bridge in the early hours of 20 August 1989.
Survivor Odette Penwarden – who now works for the Diocese of Southwark – had suggested the idea of a party on the Thames to Antonio de Vasconcellos whose birthday the river cruise was to celebrate.
She told LBC 97.3 on Thursday: "We were having a really good boogie and suddenly there was a lurch. The needle on the record flew to the side and came back again. The boat rocked a bit more and seemed to steady.
"The next thing that happened was that there was an almighty crash. The windows on one side of the boat came through, and the water just came in. It was like being in a washing machine."
At Southwark Cathedral the names of the victims were read out at the daily Eucharists on Thursday.
In the afternoon Choral Evensong – with appropriate music for the occasion – was sung by the cathedral's Merbecke Choir.
"The sinking of the Marchioness 20 years ago is still one of the worst nightmares in the history of the Thames and London but the dead did not die in vain," said Simon Hughes MP, speaking after Choral Evensong.
"A campaign by relatives and survivors has improved safety on the Thames. The legacy is many lives saved in all the years that came after."
As a result of recommendations from reports produced after the disaster the Thames now has a lifeboat service provided by the RNLI.
A permanent memorial to the victims of the Marchioness disaster can be found just inside the south door of Southwark Cathedral.
Five years ago a new Thames lifeboat was named by rugby star Lawrence Dallaglio in a ceremony held in the cathedral's Millennium Courtyard. His sister Francesca died in the tragedy.