<p>Over the past two decades, methane (CH₄) was proven to be a greenhouse gas with a global warming potential of 80 times more than that of carbon dioxide (CO₂). However, the distribution of CH₄ in the coastal waters around Korea remains poorly studied. This study examined the dynamics of dissolved CH₄ along the Goheung coast in May 2024, as part of a broader survey of CH₄ in the southern coastal regions of Korea. Dissolved CH₄ concentrations ranged from 4 to 20 nM, which is 3 to 10 times higher than the air–water equilibrium concentration. Similar concentrations were observed in both surface and bottom waters, likely due to well-mixed water column conditions. A regression analysis revealed weak correlations between CH₄ and environmental parameters, suggesting that there was no single dominant factor that controlled CH₄ dynamics in this system. Atmospheric fluxes of CH₄ in the study area ranged from 4.2 to 17.6 µmolm⁻2day⁻¹, which, although on the lower end, fall within the range reported for other coastal regions worldwide. Overall, our findings suggest that CH₄ emissions from coastal waters may increase in the near future during the summer periods characterized by bottom-water hypoxia and projected coastal warming. Therefore, the continuous monitoring of CH₄ in Korean coastal waters is essential to better understanding its dynamics, particularly in regions with increasing anthropogenic activities.</p>