An extensive series of catacomb-like tunnels or caverns exists beneath the surface of the Island. This article references those in the general area of the Barracks. These tunnels form part of an underground location used by the Others. Hieroglyphs adorn many of the pillars and walls throughout the Tunnels.
These tunnels link to similar ones beneath the Temple, a journey which would take a day and a half traveling above ground from the Barracks.
The tunnels include at least three known entrances. One can be reached by diving into a stream out in the jungle and swimming in underneath a small waterfall. Richard indicates that there is another much larger entrance which was used to to bring the bomb into the tunnels. ("Follow the Leader") It appears the Hostiles may have deliberatedly bricked up some of the entrances. Richard uses a sledgehammer to break through one of the walls to provide access to the basement of Horace's house inside the Barracks compounds. ("The Incident, Part 1")
In a large chamber somewhere within the tunnel system underneath the Barracks is where the Hostiles hid the hydrogen bomb Jughead sometime after 1954. The bomb was placed here to contain continued radiation leakage. Like many other areas in the tunnels, there are hieroglyphs on many of the pillars within the chamber. ("The Incident, Part 1")
|Picture||Name||First visit||Last visit||Reason for visit|
|Eloise Hawking||"Follow the Leader"||"The Incident, Part 1"||Lead Jack and Sayid there to recover the hydrogen bomb|
|Jack Shephard||"Follow the Leader"||"The Incident, Part 1"||Went there to find the hydrogen bomb as part of Daniel's plan to change the future.|
|Sayid Jarrah||"Follow the Leader"||"The Incident, Part 1"||Followed Eloise, Jack and Alpert there to try once again to change the future, after realizing that Ben was still alive.|
|Richard Alpert||"Follow the Leader"||"The Incident, Part 1"||Was asked by Eloise to escort her, Jack and Kate there.|
- An article "Enter: The Tunnels" from Lost: The Official Magazine indicates the 'declivity' in the Temple wall leads to another area of the Tunnels - suggesting that the tunnels beneath the Temple and those beneath the Barracks may be linked. 
- Ben's secret room is another location beneath the Barracks adorned with hieroglyphics.
- For fan theories about these unanswered questions, see: The Tunnels/Theories
- Who built the Tunnels and when?
- What was their original purpose?
- How extensive is the tunnel system?
- Was the DHARMA Initiative aware of the tunnel system before 1977?
- Grobler, Zach. (2009) Enter: The Tunnels. Lost: The Official Magazine. 25:28-31.