Related by context. Frequent words. (Click for all words.) 67 subterranean 63 Underground 57 aboveground 56 tunnels 55 underground tunnels 52 cavern 50 ventilation shafts 49 tunneling 48 overground 46 underground workings 45 tunnel 45 trapped underground 45 underground cavern 45 mine shaft 45 basements 45 mineshaft 44 underground caverns 44 ventilation shaft 44 trench 44 Tunnels 44 clandestine 43 caverns 43 tunnels dug 42 subway tunnels 42 cave 42 shaft 41 basement 41 coalmine 41 mine shafts 41 vertical shaft 41 excavation 41 caves 40 tailings dam 40 dark dank 40 mine 40 coalmines 40 elevator shafts 40 Subterranean 40 mines 39 Chilean miners trapped 39 manhole 39 coal seams 39 penstock 39 manholes 39 coal mine 39 stopes 39 Storage Tank 39 shafts 38 excavate 38 miners 38 ventilation ducts 38 trapped Chilean miners 38 methane gas 38 underground bunkers 38 underground bunker 38 adits 38 pipe 38 beneath 38 stope 38 injection wells 38 trenchless 38 breathable air 38 mined 38 undersea 37 dewater 37 Tunnel 37 heap leach pad 37 tunnelled 37 borehole 37 coal seam 37 underworld 37 cellars 37 excavating 37 adit 37 trapped miners 37 passageways 37 Cavern 37 catacomb 36 samizdat 36 dewatering 36 subway 36 dungeon 36 geologic formations 36 catacombs 36 induced polarization IP 36 digging 36 disused 36 Manhole 36 Tunneling 36 excavated 35 underground aquifer 35 bowels 35 lava tube 35 mining 35 digging tunnels 35 piping 35 underground piping 35 murky depths 35 dank 35 Chilean miner 35 electrical substation