Quick answer: Throw the defeated Bowhead Whale into the volcano, keep moving through charges, body slams and lava, then return the final trophy to the scientist.
Why this encounter matters
Mutated Bowhead Whale is the final boss and the payoff to the Volcano quest chain. It retains the lethal aerial body slam while adding falling lava that turns previously safe ground into an immediate hazard. Its fin is the final hand-in for the military-boat key.
Mutated Bowhead Whale route at a glance
| Encounter order | #10 of 10 boss and major encounters |
|---|---|
| Location | Volcano Island |
| Story status | Required for the main route or its setup |
| Summon / trigger | Bowhead Whale carcass |
| Item to keep | The Mutated Bowhead Whale fin. |
How to unlock and start Mutated Bowhead Whale
- Prepare extra cooked healing before climbing to the crater.
- Throw the defeated Bowhead Whale into the lava.
- Return to open ground and keep a clear escape lane.
- Attack after charges and body slams; never stand in lava.
- Collect the fin and return it to the hazmat scientist.
Preparation specific to this fight
- Upgrade the Assault Rifle as far as your cash allows before sacrificing the normal whale carcass.
- Fill open inventory slots with cooked healing and enter with a complete ammunition reserve.
- Inspect the open ground below the crater and choose more than one escape lane in case lava blocks the first.
- Do not trigger the fight until every co-op player has reached the arena and reloaded.
Attack patterns and safe responses
| Pattern | How to answer it |
|---|---|
| Aerial body slam | Sprint out of the projected landing area immediately. The mutated version punishes late movement even more severely than the normal whale. |
| Falling lava | Watch the ground after each pass and abandon contaminated lanes. Do not cross lava just to preserve aim or retrieve a better angle. |
| Grounded recovery | Use the moment after a charge or landing for concentrated rifle fire, then move before the arena becomes unsafe again. |
Step-by-step fight plan
- Throw the normal Bowhead Whale carcass into the crater only after final preparation.
- Return quickly to open ground with multiple escape directions.
- Fire during grounded windows while keeping the camera wide enough to see lava.
- Run the instant the boss becomes airborne; do not reload inside the landing zone.
- Rotate to fresh ground whenever lava cuts across the current route.
- Collect the fin, return it to the scientist and confirm receipt of the military-boat key.
Solo and co-op approaches
Solo
Solo players should value survival windows over continuous damage. A clean landing dodge followed by one controlled burst is repeatable; shooting through a lava-blocked route is not.
Co-op
Agree on a shared rotation direction but leave lateral spacing between players. This prevents one body slam or lava patch from trapping the entire group, while still keeping the boss in a common firing sector.
Common mistakes in this encounter
- Triggering the final boss with low ammunition because the first whale seemed manageable.
- Reusing the same running loop after lava has made it unsafe.
- Standing beneath the whale to maximize close-range damage.
- Leaving for the mainland without giving the final fin to the scientist.
If the attempt or unlock fails
If the fight fails, rebuild healing and ammunition before repeating the carcass trigger available in your save state. If the boss is dead but the ending route is locked, search for the fin and finish the scientist hand-in.
Mutated Bowhead Whale FAQ
What is different from the normal whale?
The mutated form is tougher and adds falling lava, so safe ground changes during the encounter.
Which item completes the game route?
Return the Mutated Bowhead Whale fin to the hazmat scientist to receive the military-boat key.
Can you keep using one circular route?
Only while it remains clean. Rotate to a new lane as soon as lava cuts through the old path.
What happens next
RHIB / military boat key and the mainland ending.
Open the complete Volcano Island route →
Sources, method and evidence limits
Current completion and boss guides corroborate the body slam, lava hazard, Assault Rifle recommendation, fin hand-in, military-boat key and mainland ending. Exact damage depends on difficulty and upgrades.
- Official How to Fish Steam page — official game and progression premise.
- Destructoid boss guide — encounter patterns, triggers and recommended responses.
- Destructoid complete walkthrough — island order, economy choices and story hand-ins.
- All Things How boss guide — cross-check for bait, attack windows and unlock confirmation.