2008 in swimming documents the highlights of competitive international swimming during 2008.

• 9–13 April: 2008 FINA World Swimming Championships (25 m) in Manchester, United Kingdom
• 3–8 May: 2008 FINA World Open Water Swimming Championships in Seville, Spain
• 8–13 July: 2008 FINA Youth World Swimming Championships in Monterrey, Mexico
• 9–17 August: Swimming at the 2008 Summer Olympics in Beijing, China
• 20–21 August: 10 km marathon swimming at the 2008 Summer Olympics in Beijing, China
• 7–15 September: Swimming at the 2008 Summer Paralympics in Beijing, China
• 25–26 October: Marathon swimming at the 2008 Asian Beach Games in Bali, Indonesia
• 2008 FINA Swimming World Cup
  • 10–12 October: Belo Horizonte, Brazil
  • 17–18 October: Durban, South Africa
  • 25–26 October: Sydney, Australia
  • 1–2 November: Singapore
  • 8–9 November: Moscow, Russia
  • 11–12 November: Stockholm, Sweden
  • 15–16 November: Berlin, Germany

• 30 July – 3 August 2008 European Junior Swimming Championships in Belgrade, Serbia
• 1–7 December: 2008 African Swimming Championships in Johannesburg, South Africa
• 11–14 December: European Short Course Swimming Championships 2008 in Rijeka, Croatia

Long course

Dates	Event	City
22–29 March	Australian Championships	Sydney
31 March – 6 April	British Championships	Sheffield

Short course

Dates	Event	City
27–30 November	Swedish SC Championships	Stockholm