[liotier]

Other large cycling tunnels:

- Rotterdam's Maas Tunnel: https://www.youtube.com/watch?v=X6UUinjhQgM

- Antwerp's Kennedytunnel: https://www.youtube.com/watch?v=L7CsUnQ5BY0

- Paris' Parc des Rives de Seine's tunnel: https://www.youtube.com/watch?v=bAIXHVolUmg

- England's Tyne Tunnel: https://www.youtube.com/watch?v=bR4je-ndz7E

- Nam Han River's tunnel: https://www.youtube.com/watch?v=nFNrxpeLtAU

- Lyon's Tunnel de la Croix-Rousse, with yours truly pedalling through it: https://youtu.be/JDvBNsVMkRc?list=PLBcwv3gb0JkpDlYfh-yfBWqtS...

[arethuza]

Also the Innocent Railway tunnel in Edinburgh - not that long but with an interesting history (a railway tunnel that predates steam):

https://blog.historicenvironment.scot/2021/02/innocent-railw...

[bombcar]

Snoqualmie Tunnel: https://www.youtube.com/watch?v=s7Hze1R8Gg8 (more of a hiking trail, but you can bike it if you have lights). Not purpose-built; it's an old train tunnel.