TL;DR: Safe order is "NPC task → protected item → boss trigger → boss drop → NPC hand-in → Radar/next island". Normal catches fund progress; special bait and boss drops unlock progress. If you can't classify an item, keep it until the current NPC chain is done.
Spider Crab trigger route. Selling or cooking before the boss hard-locks you.
Boat Keys / route hand-in. Don't leave the island without handing in.
Giant Piranha trigger. Don't let teammates drop the items.
Desert route hand-in. Don't sail away before NPC confirmation.
Pufferfish trigger. Treating Carrot as normal bait breaks the line.
Rocks route hand-in. Don't lose it in arena clutter.
Albatross setup. Selling, cooking or eating it mid-route breaks progression.
Volcano route hand-in. Don't leave before the marker/route advances.
Late boss route. Don't experiment with cooking first.
Let the host or one chosen player carry every special item and boss drop until the route advances. Others can farm money, fight, or scout, but should not casually pick up and sell route items.
Normal catches fund progress; special bait and boss drops unlock progress. If you can't classify an item, keep it until the current NPC chain is complete.
What should I not sell? Special bait, route items, and boss drops before hand-ins.
Can I cook quest items? Avoid cooking anything tied to NPC tasks, boss triggers, or boss drops.
Who holds quest items in co-op? The host or one route owner.
Why doesn't my route advance? You likely missed a boss drop, wrong NPC, wrong owner, or unfinished hand-in.
About 80% of "stuck" moments aren't about fighting — they're about selling, cooking, or handing a key item to a teammate. Lock route items on the host and the five islands flow.
Items clear? See all five islands for each island's NPC and hand-in order; for co-op roles see the co-op guide.