During the 2018–2019 Antarctic summer, the Korea Polar Research Institute and the University of Texas Institute for Geophysics collaborated on a helicopter-based ice-penetrating radar (IPR) survey over the active subglacial lake Cheongsuk (SLC), located in the midstream of the David Glacier, Terra Nova Bay, Antarctica. This study investigates the relationship between SLC water levels and fluctuations in glacial surface elevation (up to 3.6 m) and delineates subglacial lakes within the study area. We provide a comprehensive analysis based on integrated data from IPR (2018), Sentinel-1 double-differential interferogram synthetic aperture radar (DDInSAR) (2017–2022), ICESat-2 laser altimeter (2019–2022), and KOMPSAT-5 synthetic aperture radar (2021 and 2023). The concave bedrock structure and low hydraulic head areas concentrate glacier meltwater, facilitating water accumulation and retention, forming a lake. The SLC is identified based on bed elevation, hydraulic gradient, and relative reflection intensity. Its area approximately 1/7 of the lake area estimated through remote sensing. Our analysis suggests that variations in water supply and discharge along the subglacial channel network influence lake water levels, evidenced by a surface elevation increase of up to 3.69 m in the SLC area from 2019–2022. Additionally, the presence of crevasses and incoherence in DDInSAR imagery suggests that subglacial lakes impact glacier flow velocity.