Swimmers as young as four took part in the Belper Marlin SC Mini-Marlin Championships at Heanor Leisure Centre, aiming to win medals and trophies.
The annual event also marked the end of an era for the club.
Irene Hallsworth, who has run the Mini Marlins for many years, retired.
Irene has been with the club for more than 25 years
A club spokesman said: “She has given her time freely and helped countless numbers of childrento realise their true potential and build confidence in their swimming.
“Irene was her usual modest self and most of the emotion came from her young prodigies, Hannah and Kathryn, who were also taking a step back from coaching due to their study commitments.
“The children, as you can imagine, were more interested in unwrapping presents, but the parents certainly appreciated the effort that had gone in to enable their children to perform so well in the competition.”
The Marlins’ head coach, Mike Brett, attended the event and spoke of Irene’s dedication and commitment to the club.
All the youngsters taking part were presented with medals and received a gift from Father Christmas.