The Underdark is one of the very important areas in the Baldur's Gate 3 game. There are four ways to enter. I believe there are still many players who don't know how to enter. The editor below will introduce how to enter the Underdark. There are Friends who need it, please take a look, I hope it can be helpful.
1. Method one
Go straight down from the Goblin Temple of Selun.
2. Method two
From the Spider Queen's cave, use Featherfall to jump down into the pit.
3. Method three
Enter the poisonous tree from the hag house fireplace, climb up and pass through the hidden door and transmission circle.
4. Method four
Take the path of advancement, rescue the two archers trapped in the cave, get the code word, and go to Woking's resting place to enter the Zhentarim. Just go up to the second floor and get off the elevator.