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.
And in the meantime, let’s float back in time to these scenes from Farringdon, Hetton, Hendon, Sunderland Aquatic Centre and Peterlee.
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.
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.
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