Burrowing allows Zerg ground units to hide underneath the surface. While burrowed, units can only be targeted while in the presence of an enemy Detector or while affected by Fungal Growth. Most units cannot move while burrowed but Infestors and Roaches, upon which they do not receive the speed bonus for being on creep. While burrowed, units do not contact other non-burrowed units aside buildings, although they do contact other burrowed units in Starcraft II. Most units have their sight reduced by 4 while burrowed. The exceptions to this are the Infestors, Banelings and Swarm Hosts, which do not suffer from reduced vision when burrowed, and Infested Terrans, which have their sight reduced by 5. Burrowing requires a brief period to complete, which varies between different units.
Similar to cloaked units, burrowed units can be spotted by keen players who notice a shadow-like cloud on terrain.
Burrow is a research that enables this for almost all Zerg ground units researched from any Zerg Hatchery. Larvae, Eggs, Cocoons, Broodlings, Nydus Worms, Changelings and Locusts are the only units that cannot learn to burrow.
Durations vary. There is also a random element that gets added to this duration. All numbers in in-game seconds:
Note: Italics to indicate units with (optional) mobility while burrowed.
- Roaches can harass the enemy once they are equipped with the Tunneling Claws upgrade, allowing for undetected movement underground.
- Roaches with Tunneling Claws are also capable of maneuvering under Protoss Force Fields preventing a Protoss contain.
- Burrowed units are an effective means of sandwiching an enemy army from both sides, cutting off reinforcements, picking off vulnerable units (such as High Templars) and various other strategic plays.
- The use of Burrow is an effective way of microing units who are taking damage out of danger (assuming there is a lack of detection from the opposing player).
- Banelings can be burrowed as "mines" and unburrowed or detonated once a Marine, or equivalent light-unit, army is above them allowing for devastating splash damage.
- Zerglings or any other Zerg ground unit can be burrowed at an enemy expansion before it is taken to prevent the placement of a Command Center, Nexus or Hatchery.
- Lurkers must be burrowed to enable attacks with Seismic Spines.
- In Heart of the Swarm, Swarm Hosts needed to be burrowed to Spawn Locusts until the balance update to Patch 2.1.9. This is not the case anymore.
Synergy with other abilities
- Roaches' native and/or upgraded ability to regenerate faster only kicks in when burrowed.
- Infestors may use the spell Infested Terrans while burrowed.
- Infestors or Roaches can move "across" lowered Supply Depots while burrowed. Furthermore, having a burrowed unit on top of a lowered Depot prevents it from being raised.
- Unlike cloaked units such as Observers or Dark Templars, they cannot be revealed with the help of an EMP Round.
- Unburrow can be autocast, by right clicking the Unburrow icon or pressing + . This will cause the unit to automatically unburrow when an enemy ground unit approaches. The range at which unburrow is autocast varies from unit to unit.
- Creep Tumor is a Zerg building which automatically burrows itself upon completion.