Here is the list of coordinates for all 50 Sonic Periscope Audio Logs (10 in each of 5 different zones) for the monthly achievement + 100 karma per log per day.
Each Periscope can be grabbed once per character per day.
Also included is a (very) partial list of Super Mysterious Chests I encountered while running through these zones. Each one appears to respawn every ~5 minutes. Good luck.