To maximize the potential of big geospatial data streams, they shall be processed on high-performance computing (HPC) infrastructure, whereas local code shall be adopted to use this infrastructure efficiently. This paper presents a non-profit initiative, GEO-OPEN-HACK, that aims at lowering the technical barrier for environmental scientists through one-week hackathons on open-source HPC processing approaches, such as openEO, Pangeo, and OEMC. We present the above solutions, hackathon setup, and analysis based on the pre-event questionnaire about the participants’ big data projects.