Target poison-pufferfish near reefs and larger islands for explosive goo collection. Using your bow from a safe distance, swim backward while shooting at these yellow-green aggressive fish, and be ready to dodge their explosive attacks. Once you've gathered the goo, process it through your smelter station, just like you would with metal or glass materials.

A decent tip is to scout the area first since these fish tend to cluster together, making it easier to gather multiple drops in one trip. When swimming back to collect the goo, watch for additional pufferfish that might have spawned nearby, and remember that net canisters need quite a bit of powder so plan on making multiple trips to stock up properly.