TV presenter Adrian Chiles joined 500 others to help break the world record for the largest sub-aqua dinner party.
The food was specially prepared in jelly
The Guinness Book of Records is set to confirm exactly how many guests sat down to the gourmet meal of smoked salmon, vegetables and toffee apple.
The previous record for the largest sub aqua dinner party was 100, set in 1991.
Wearing dinner jackets and ball gowns, diners indulged in their three-course meal at the outdoor swimming pool at The Park Club in Acton, west London.
The food - which was served to sittings of about 20 people every 20 minutes - was prepared in jelly to stop it from disintegrating in the water.
To eat, the diners had to remove their aqua lung mouth pieces, fork in the food and then replace the breathing equipment while pressing a button to purge away the water.
The event raised more than £200,000 for charities including Save the Children, The Shooting Star Hospice, Breakthrough Breast Cancer and The British Heart Foundation.
Experienced divers from the London School of Diving were on hand to assist diners and serve the food during the event.