London Buses route SL2 is a Transport for London contracted Superloop express bus route in London, England. Running between Walthamstow bus station and North Woolwich, it is operated by Arriva London.

The route partially parallels routes 123 and 366.

On 21 July 2023, a consultation for route SL2 was opened by Transport for London, and closed on 4 September the same year.^[1][2] It was awarded on 20 October 2023, and was introduced on 2 March 2024, using existing Alexander Dennis Enviro400H Citys.^[3] It is operated by Arriva London as a variation to its route 123 contract that it parallels between Walthamstow and Ilford.^[4][1]

Route SL2 operates via these primary locations:^[5]

• Walthamstow bus station for Walthamstow Central station
• Walthamstow Market
• South Woodford
• Clayhall
• Gants Hill station
• Ilford station
• Barking station
• University of East London Docklands Campus for Gallions Reach station
• North Woolwich for the Woolwich Ferry

The route operates at a frequency of a bus every 12 minutes on weekdays and Saturdays and a bus every 15 minutes on Sundays.^[6]

From June 1996 until August 2002, a previous route SL2 ran in Central London, connecting the mainline railway stations at Paddington, Marylebone, Euston, St Pancras, King's Cross, Liverpool Street, Fenchurch Street, London Bridge, Waterloo and Victoria.^[7][8] The route was operated by Thorpes and branded as Stationlink, running an hourly (anticlockwise) circular service, with route SL1 operating in the reverse direction. SL1 and SL2 were replaced by routes routes 205 and 705 in August 2002.^[7][8]