How to Fish Island Progression: Unlock Every Island

The first island unlock has three separate actions that many guides collapse into one: return the Spider Crab proof, pick up the boat key, then buy the handheld Radar for $10. Equip the Radar and follow its green marker toward the northwest; owning the boat alone does not reveal the route.

Island unlock chain

Destination	Required chain	Proof that it worked
Island 2 · Forest	Empty Beer Can → Spider Crab → return the requested proof → take boat key → buy $10 Radar	Handheld Radar shows a green marker northwest
Island 3 · Desert	Pick up 3/3 leeches → Modified Leech → Giant Piranha → return its skeleton	New coordinates/marker appear after the hand-in
Island 4 · Rocks	Complete tourist/Needlefish request → receive Carrot → Pufferfish → return its fin	Island 4 route appears
Island 5 · Volcano	Professional Boss Lure → Tuna → use Tuna body for Albatross → return Albatross head	Island 5 route appears
Mainland ending	Fish Bucket → Bowhead Whale → throw body into volcano → Mutated Bowhead → return final fin	Military boat/RHIB route becomes available

The trigger items and hand-ins are multi-source walkthrough facts. Patch 1.0.5 officially fixed the bug that once allowed travel to locked islands, so pre-1.0.5 skip routes are obsolete.

When Island 2 does not appear

What you see	Most likely missing action	What to do
No boat key	Spider Crab request was not accepted or its proof was not handed in	Return to the Lighthouse Keeper with the distinct boss proof
Boat works, no marker	Radar was never bought or is not equipped	Buy the $10 Radar from the Lighthouse Keeper area and hold it
Radar has a green marker	The route is available	Sail northwest toward the marker; do not wait for a map menu
Radar was lost	Item may have been dropped, sold or left on another player	Search the Lighthouse shop and crew inventory; buying again is player-reported, not guaranteed

When a later island does not appear

Work backward from the missing marker: active NPC request → exact bait → intended boss → named trophy → correct NPC hand-in. Ordinary meat cannot replace a skeleton, fin, head or whole body. In co-op, the host’s quest state and the player carrying the trophy must both be checked before anyone leaves.

Sources: How to Fish on Steam, Dazed Games Patch 1.0.5, current walkthrough sources and Steam Community reports, checked 2026-08-27. The $10 Radar and northwest marker are repeated player/guide observations rather than patch-note claims.