And we want to help you get into the spirit of the occasion with a look back at some archive swimming scenes from across Wearside and County Durham.
More than 450 pools across the UK are hosting Swimathon sessions until Sunday, including a number in the Sunderland area.
Find out more at https://www.swimathon.org
And in the meantime, let’s float back in time to these scenes from Farringdon, Hetton, Hendon, Sunderland Aquatic Centre and Peterlee.
Find out more at https://www.swimathon.org
5. Champions in consecutive years
Back to 2003 for this view of pupils from Dame Dorothy Primary School who had won a swimming gala for the second year running. Photo: MM
6. All for charity in Farrindon
Pupils from Farringdon Academy swam the equivalent distance of crossing the English Channel, to raise money for Project Gambia in 2014. Photo: Picture by David Allan
7. Ready to train in 2005
Members of the City of Sunderland Swimming Club were pictured before a training session at the Raich Carter pool in 2005. Photo: TY
8. Lots of support in Hetton
A swimming gala at Hetton Marina for four Sunderland schools. Who do you recognise in this photo from 8 years ago? Photo: Picture by Sophie Bell