Subterranean estuaries (STE), the zone where fresh groundwater mixes with saltwater, influence the chemical fluxes to the ocean. In this mixing zone, the chemical elements carried by the groundwater undergo biogeochemical transformations before being discharged to the ocean. Therefore, the aim of the present study is to understand the biogeochemical processes at the STE of a section of the Odisha coast (east coast of India). The coast is tidally influenced and the climate is tropical with an annual rainfall of about 1550 mm. Sampling took place in the pre-monsoon (May 2024) and post-monsoon (October 2024) seasons. Seawater, groundwater and sediment porewater (down to 125 cm) in transects along the coastline in the intertidal zone were sampled. Samples were collected for the measurement of several parameters including nutrients, major and trace elements and carbon species. The surface and pore waters showed differences in salinity values between the two campaigns: during the pre-monsoon, salinities were up to 36 PSU, while after the monsoon, the salinities decreased to a maximum of 30 PSU, and values close to 2 were found in the porewaters. During the post-monsoon season, more low salinity spots were detected along the coastline, which may be due to the more pronounced hydraulic gradient after the monsoon season. Salinity values were positively correlated with beach elevation, and a seepage line indicating the presence of diffuse SGD was found at about 2 m above the sea level. This suggests that submarine groundwater discharge is an important phenomenon in the region leading to the formation of an STE. The concentration of nutrients in the different systems suggests that the STE plays a role in the transport of nutrients to the sea, with an indication of nutrient consumption, which has a positive impact on the nutrient load to coastal waters in areas of high population density. Further studies will continue to better understand the final subterranean elemental fluxes to the coastal waters of this interesting location.