In Patch 10.1, you can enter Zaralek Cavern from 3 different places.
The first entrance is located between Valdrakken and Ohn’ahran Plains. When you look at the map of Ohn’ahran Plains, the entrance is at 49.21 54.75.
When you open the map of Thaldraszus, the entrance will be at 29.77 62.97.
Another entrance to the zone can also be found in Ohn’ahran Plains at 36.11 59.01 near Teerakai.
The final entrance is found at 18.75 23.37 in The Azure Span (Three Falls Lookout).
Zaralek Cavern is located directly beneath the Dragon Isles, and depending on the entrance you use, you will end up in 3 different locations. There’s no loading screen and the transition between zones is seamless.