Northern peatlands are significant pools of stored carbon. Understanding of seasonal dynamics of peat water table (WT) is the key to improve spatial models of material flows and gas exchange in those landscapes. Since synthetic aperture radar interferometric (InSAR) observables are influenced by soil moisture variations, the objective of this study is to examine the ability of Sentinel-1 long term InSAR coherence magnitude (calculated using a single master image) to characterize seasonal dynamics of peatland WT over 3 years of different climatological conditions. We show how in the open bog the coherence can be preserved more than 6 months and is related to peat WT difference in favourable weather condition. The second degree polynomial regression model can describes the relationship between coherence and WT with Root Mean Squared Error RMSE 0.047 (p < 0.001). These findings suggest long term InSAR coherence has potential to characterize seasonal bog WT fluctuations, especially during dry summers or in intensive drainage affected sites with high discharges.