|Complete Bright Lights, Flying City||16||Sanctuary (Tannis)||2611 XP, 4 Eridium|
Tannis has hidden her journals on the opening of the vault and wants you to retrieve them for her. Fast travel to The Highlands - Extraction Plant and get on the bridge nearby, looking for a set of stairs that lead downwards and connected to the bridge. You don't want to go higher or lower than this level, but instead look for a beam jutting out from the edge, with another beam being perpendicular to it. Jump onto the other beam and head inside the shack to find the journal.
This next one can be tricky, as it's possible for you to die in trying to get to it. Cranky's Old Pond is an area located in the northeast corner of the map. Head there and through the shack to find the familiar blue light emanating from the boat in the water. This boat is out of bounds, meaning that you need to hurry up to grab it before the game automatically kills you.
For the third journal, find the southern of the two exits leading to The Highlands - Outwash on your map. The area just north of it is a Hyperion camp with Loaders and Personnel, with two turrets guarding the entrance. Go through it and when you find some stairs on the right, take them, as they will lead to a higher area with more enemies.
Eventually, you should reach the location of the journal, which is behind an electrified barrier. Face the barrier and look up to spot the switch for it on the wall of the tower. Shoot it with any gun to open destroy the barrier, then simply walk inside and grab the journal.
The last journal is located in Frothing Creek Mill and should be easy to locate if you've gotten the other three first. If not, then it is south of the one in the Hyperion base. This one is located inside of a container that has the front entrance blocked by a bent gate. If you go around back, you'll notice that the ramp is stuck by some strange sacs. Shoot them to lower the ramp and go snatch the journal. Return to Tannis in Sanctuary once you've gotten all four journals.