If you lizard leap toward the locked area from where Prog spawns and either slowfall or engineer parachute, you can make it over a broken part of the wall right into the locked area. You can also go into the thunderforge if you are a druid and can wild charge the goats up the rocks. I'm sure there's another way as well, but that's how I did it.
Alternatively, and more creatively, you can do this with a goblin, a druid, and a priest if you're bringing friends. Have the goblin rocket jump from a rock on the east shore (just before the locked area's docks) to the ledge, then the druid can wild charge, and use the priest's lifegrip symbiosis to bring the priest, or whoever else you are bringing with you. That's how we got in the first time, until I accidentally got in the aforementioned way trying to land in a tree lol. There are lots of spawns up there, and untouched. You can do 5 or 6 of the achievements while you're there as well. Have fun.