Turns out I did not know where to go, but I finally reached it. I now have 100% completion. Great game! Here is a hint on where I got confused, as always encoded using rot13.com:
lbh unir gb trg gur fgne ng 5,10, abg sebz gur raq frpgvba va 7,8. gung vf na rkvg bayl, hagvy lbh unir nyy bs gur fgnef.