https://wow.gamepedia.com/Shadowlands#Appearances
That lists all the times the Shadowlands have appeared, many of which involves us traveling directly into it.
Notably, that’s how we get our Deathchargers.
Also from this expac.
Centuries ago, Summoner Mepjila cursed the followers of Kimbul to constantly relive their battle with her naga forces as spirits for eternity. Kimbul sends an adventurer into the Shadowlands to slay Mepjila’s spirit and free his followers from her curse.
Vol’jin’s spirit and a Horde adventurer traveled through Orgrimmar in the Shadowlands as Vol’jin relived the day of his death and realized it was not the loa who told him to make Sylvanas Windrunner warchief.