Lanternfishes, which are important prey for demersal and diving predators at Macquarie Island in the Southern Ocean, have spatial patterns of distribution over the Macquarie Ridge that suggest biomass is enhanced where the Subantarctic Front (SAF) interacts with a break in the topography of the Ridge (the ‘Ridge Gap’). The summertime lanternfish assemblage, documented here for the first time, comprised 23 taxa, dominated by Krefftichthys anderssoni and Gymnoscopelus braueri. Mean lanternfish biomass was highest (3.13 g 1000 m–3) in the Ridge Gap habitat. Lowest mean biomass (0.71 g 1000 m–3) was recorded up-current of the SAF over the Abyssal Plain and intermediate biomass (1.26 g 1000 m–3) was recorded over the Macquarie Ridge. At Ridge Gap, a high abundance of K. anderssoni was recorded in the shallowest stratum (0–250 m) during the day. We hypothesised that the oceanographic–topographic interaction between the SAF and Ridge Gap creates eddy systems and productivity fronts that passively entrain and/or actively attract lanternfishes to the Ridge Gap area. This oceanographic–topographic interaction depends on the spatial stability of the SAF in relation to the Macquarie Ridge and Ridge Gap and is vulnerable to climate-mediated change that may have flow-on effects to predators with commercial and conservation significance.