Salt marsh hydrology research in recent years has focused on marsh dynamics in warmer climates or during the summer. Little is known about the influence of winter conditions in colder regions, where snow and ground ice can influence marsh hydrology, sediment thermal regimes, and biogeochemistry. These dynamics are highly relevant for PEI, which experiences seasonal sea and ground ice formation and melting. The overall goal of this project is to investigate present and future hydrologic, thermal, and biogeochemical dynamics in a salt marsh along the north shore of PEI. The project focuses on the winter season dynamics and the influence of snow, ground ice, and sea ice on the integrated salt marsh-bay system. To monitor groundwater dynamics, we installed conductivity, temperature, and water level loggers in a cross-shore transect (low to high marsh) of salt marsh piezometers. At each piezometer, we took proximal greenhouse gas (GHG) flux measurements at GHG collars using a LI-7810 Trace Gas Analyzer to better understand the influence of snow and ground ice on winter GHG fluxes. To assess spatial distribution in surface and subsurface conditions (including snow, temperature, ice, and salinity), we conducted ground penetrating radar, thermal infrared, and LiDAR surveys with drone-mounted sensors and mapped ground electrical conductivity with a frequency-domain electromagnetic geophysical instrument (GEM-2). The data are being used to develop a better understanding of present-day winter salt marsh dynamics to inform the development of process-based models to investigate how these systems may respond to atmospheric and oceanic climate change.