Although it is common for ant surveys to uncover previously uncollected species, a recent study of subterranean ants in Amazonian Ecuador has indicated that an entire ant fauna may remain largely undiscovered. Here we report on the first systematic investigation of subterranean ants in northern Australia, in order to assess the extent to which the high abundance and diversity of subterranean ants in Amazonia is apparent in tropical Australia. We use a novel sampling technique that combines elements of an attractant bait and a pitfall trap, and allows many traps to be deployed simultaneously. Our main study was conducted at three closely approximated sites in Darwin, where the local ant fauna has been intensively surveyed using conventional (above-ground) sampling techniques. The 720 traps deployed resulted in 421 species records, representing 29 species from 17 genera. Sixteen of these species have cryptobiotic morphology, with four recorded here for the first time. Remarkably, one of these four (a blind species of Solenopsis) was the second most frequently caught species in subterranean traps, with 70 records. Ant abundance, species richness and composition varied markedly between sites, despite site similarity in soils and vegetation. Total ant records were greater in the middle compared with start of the wet season, declined with depth, and were greater after 4 days than one. Sampling at six sites in the Mitchell Falls area of the northern Kimberley region, 1,200 km southwest of Darwin, also revealed several cryptobiotic species new to science, including a new genus record (Pseudolasius) for Western Australia. Our underground sampling has therefore revealed an abundant and diverse subterranean ant fauna in northern Australia, containing many cryptobiotic species not previously collected. We use our results to provide methodological guidelines for most effectively sampling this fauna. Combined with the Amazonian study, our findings indicate that a specialist subterranean ant fauna, including numerous species remaining to be discovered, might be a feature of tropical landscapes throughout the world.