Submarine Groundwater Discharge (SGD) and Seawater Intrusion (SWI) are opposing yet interconnected processes along the land-sea continuum that shape coastal groundwater dynamics. This study identifies SGD and SWI zones along the water-stressed Odisha coast using a multi-proxy approach and quantifies SGD and associated chemical fluxes through seepage meter measurements. A total of 340 samples (85 per season: 30 porewater, 30 seawater, and 25 groundwater) were collected across ~145 km of coastline during two pre- and two post-monsoon seasons. Elevated groundwater electrical conductivity (>3000 μS/cm) indicated three probable SWI sites, while low porewater salinity (<32 ppt in pre-monsoon, <25 ppt in post-monsoon) suggested four SGD zones. These findings were validated by hydraulic gradients (positive >10 m near SGD, negative <0 m near SWI) and anomalous sea surface temperature patterns. Hydro-geochemical analysis and stable isotopic signatures further confirmed the identified sites. SGD fluxes, measured via Lee-type seepage meters, ranged from 2940.91–4247.97 m³.m⁻².y⁻¹ in post-monsoon (Dec 2022) and up to 1503.13 m³.m⁻².y⁻¹ in pre-monsoon (May 2023), among the highest global seepage rates. Nutrient fluxes varied from 1308.14–12863.81 mmol.m⁻².y⁻¹ (total carbon), 154.3–849.9 mmol.m⁻².y⁻¹ (dissolved silica), 48.35–261.54 mmol.m⁻².y⁻¹ (total nitrogen), 57.04–203.65 mmol.m⁻².y⁻¹ (nitrate), and 0.85–9.12 mmol.m⁻².y⁻¹ (phosphate). Heavy metal fluxes followed the order B > Sr > Li > Ba > Al > As > Fe > Cu > Co > Ni > Mo > Be > Mn. Despite high seepage rates, relatively low chemical fluxes suggest dilution, limited contaminant sources, adsorption, or biogeochemical attenuation. This study provides the first SGD flux estimates from Odisha’s coastal plains, emphasizing the need for further research on subterranean estuarine processes to refine our understanding of fresh-saline interactions and material transport mechanisms.