As the name of this location suggests, they are a pair of caves situated right next to each other on the Eastern side of the South Crevasse. An aggressive Bluntnose Sixgill Shark that patrols the area makes its territory known by attacking encroaching divers, so it is advised for players exploring this area to take extra care in observing their surroundings.
The Westernmost of the two caves is home to a group of Giant Isopods and the Easternmost of them is filled with Vampire Squids. However, the creatures in the Eastern cave will eventually have to share their home with the Grave Keeper, a legendary Giant Isopod that is much larger than the others and has a unique blue-green colouration.
Another unique find in the Eastern cave is Cleo's Treasure, a treasure that the player can obtain by using the Multisensor in the cave (this will complete the quest titled "Survey of the Depths" once the treasure has been appraised by Nancy). There are also several other salvageable items in the Caves, but Cleo's Treasure is by far the most interesting of the bunch.