How do I get to Drydock Grotto?
Solution 1:
The entrance is in one of the new Skritt tunnels that open when you defeat the bandits in the area. While doing this Living Story chapter (Seeds of Truth), it will show you where the entrance is since it is necessary for the plot.
EDIT:
Sorry, i mixed up the two areas. Here is your answer: In Picaroon Scratch (that cave next to the WayPoint), there is an event where you have to kill bandits. After that, a gate will open and show you stairs going down to a giant cave: Thats where the waypoint is.