Caves
Beneath Arrakis' surface is a vast network of caves and tunnels, and have been the natural respite for all seeking shade from the deadly heat during the day. The Fremen have a long history of using them to hide from the prying eyes of the Imperium and other offworlders, and many of the caves still bear echoes of this culture in wall carvings, paintings and watersealed entrances. Some caves hold a particular significance to the Fremen, such as the sacred temple sites of the Trials of Aql
Caves are the primary source of 
EMF Generator and
Micro-sandwich Fabric. They usually have Maas Kharet or Scavengers in or around them, and some contain various Fire or Posion traps
Hagga Basin Caves
Map
Deep Desert Caves
Caves can be found in all areas of the Deep Desert, both in PvP and PvE areas