In September 2018, Joost visited the island of Guam (USA). Together with Prof. Tom Schils from the University of Guam, he scanned coral reefs using the PlanBlue technology. This project was executed as part of the NASA Geocore program. At the same time, Joost conducted a pilot with Dr. Matthias Egger from The Ocean Cleanup. Together they monitored plastic waste on Guam's seafloors, and validated the PlanBlue technology for this purpose as well.