Coastal wetlands are long-term carbon sinks capable of sequestering carbon for millennia. However, for coastal wetlands to have a net cooling effect on the atmosphere, their carbon storage must exceed their greenhouse gas (GHG) emissions. Meanwhile, the conditions that facilitate carbon sequestration favour the production of several potent GHGs, including methane (CH4) and nitrous oxide (N₂O). The direction and magnitude of these fluxes may be modulated by multiple environmental drivers, including temperature, salinity, and inundation dynamics. While there is increasing understanding of coastal wetland CO2 fluxes, little research has been conducted on the drivers of CH4 and N₂O, particularly within the Australian context. In summer 2022 and winter 2023, soil-atmosphere fluxes were analysed via Fourier-transform infrared (FTIR) spectroscopy using 12 chambers installed over an elevation gradient spanning mangrove, lower saltmarsh, upper saltmarsh and swamp oak forest ecosystems at Towra Point Nature Reserve, Botany Bay, New South Wales, Australia. These data were compared with water-level loggers installed adjacent to each vegetation community, recording temperature, salinity, and water level to understand the physicochemical drivers of GHG sediment flux variation. Site-wide mean sediment CO2 fluxes (2.96 × 10-05 μg m-2 s-1) were several orders of magnitude larger than both CH4 (-1.56 × 10-08 μg m-2 s-1) and N₂O (-2.12 × 10-09 μg m-2 s-1), even when adjusted for global warming potential (GWP). Vegetation communities acted as CH4 and N₂O sources and sinks in different seasons. A two-way ANOVA was used to examine the effects of vegetation community and season on fluxes, and a multiple linear model to explore the physicochemical drivers of flux variation. Generally, GHG fluxes were higher in summer than winter, likely due to enhanced microbial activity in warmer sediment. As expected, the low elevation mangrove community was a moderate CH4 source due to the anoxic conditions that facilitate anaerobic respiration. In contrast, the lower and upper saltmarsh acted as mean CH4 sinks (-6.31 × 10-08 and -5.008 × 10-08 μg m-2 s-1 respectively). Sediment N₂O fluxes were complex and, in some cases, switched from sources and sinks between seasons. Significant upper saltmarsh summer sediment N₂O efflux was observed (2.24 × 10-08 μg m-2 s-1). Variation in the sediment flux of oxygen-containing molecules (i.e., CO2 and N₂O) was partly explained by changes in temperature and salinity. In contrast, variation in CH4 sediment flux was driven primarily by inundation dynamics. The opposite behaviour of oxygen and non-oxygen molecules in response to physicochemical