Lakes are hotspots for CH₄ and CO₂ effluxes, but their magnitude and underlying drivers are still uncertain due to high spatiotemporal variation within and between lakes. We measured CH₄ and CO₂ fluxes at high temporal (hourly) and spatial resolution (approx. 13 m) using 24 automatic floating chambers equipped with continuously recording sensors that enabled the determination of diffusive and ebullitive gas fluxes. Additionally, we measured potential drivers such as weather patterns, water temperature, and O₂ above the sediment. During five days in autumn 2021, we conducted measurements at 88 sites in a small, shallow eutrophic Danish Lake. CH₄ ebullition was intense (mean 54.8 μmol m⁻² h⁻¹) and showed pronounced spatiotemporal variation. Ebullition rates were highest in deeper, hypoxic water (5–7 m). Diffusive CH₄ fluxes were 4-fold lower (mean 15.0 μmol m⁻² h⁻¹) and spatially less variable than ebullitive fluxes, and significantly lower above hard sediments and submerged macrophyte stands. CO₂ concentration in surface waters was permanently supersaturated at the mid-lake station, and diffusive fluxes (mean 919 μmol m⁻² h⁻¹) tended to be higher from deeper waters and increased with wind speed. To obtain mean whole-lake fluxes within an uncertainty of 20 %, we estimated that 72 sites for CH₄ ebullition, 39 sites for diffusive CH4 fluxes and 27 sites for diffusive CO₂ fluxes would be required. Thus, accurate whole-lake quantification of the dominant ebullitive CH₄ flux requires simultaneous operation of many automated floating chambers. High spatiotemporal variability challenges the identification of essential drivers and current methods for upscaling lake CH₄ and CO₂ fluxes. We successfully overcame this challenge by using automatic floating chambers, which offer continuous CH₄ and CO₂ flux measurements at high temporal resolution and, thus, are an improvement over existing approaches.