Highly permeable sandy sediments dominate the productive continental shelves and likely play a key role in global biogeochemical cycles. Despite their prominence, we currently have a poor understanding of how sandy sediments function and how they will respond to climate change. This knowledge gap is largely due to the difficulty in accurately sampling sandy sediments, as no method yet exists for measuring a range of analytes while accounting for advective pore-water flow in these dynamic environments. To help address this, we developed a new pore-water sampler that, when coupled to a portable mass spectrometer, can measure a suite of dissolved gases (e.g., O 2 , N 2 , Ar, CO 2 , and CH 4 ) in sandy sediments. Here, we present a series of laboratory experiments to validate and calibrate the instrument, as well as proof-of-concept submersion and field tests. Our results show that with some design improvements, our system will be capable of sustained (hourly to diel) in situ measurements in sandy sediments. This new approach has the potential to provide a large volume of high-quality data in any aquatic system with sandy sediments and thus greatly advance our understanding of biogeochemical processes occurring in these environments.