You may find this blue chest while you are exploring on Balmorra, but you won’t be able to open it until you’ve found a hidden vendor else where on Balmorra.
This datacron is in roughly the same spot as the Republic-only Balmorra Blue Mastery Datacron.
Quick Travel / Taxi / Walk
[HEROIC 2+] Project Hexapod heroic shuttle is closer if you don’t have the quicktravel.
Get Lost Code Cylinder
Walk across the lake to the vendor named Ba’teil, you can see her vendor marker on the map.
You will want to buy a Lost Cylinder from her, it only costs 5,000 credits.
Find the Chest
Tale the Lost Code Cylinder item to a chest that’s glowing blue on a broken bridge in the middle of the Bugtown map. If you have the code cylinder, the chest will open and have the datacron inside!