How to Fish: How to Throw the Whale into the Volcano and Beat the Final Boss

The whale on Volcano island in How to Fish looks like the last obstacle, but killing it is only the setup. Once you defeat the regular Bowhead Whale, you carry its body to the top of the volcano and throw it into the lava. That single action spawns the Mutated Bowhead Whale, the game’s true final boss, with no pause in between to restock.

Quick answer: Give the hazmat scientist five Volcano fish to get the Fish Bucket, use it to hook and kill the Bowhead Whale, store the carcass, climb the volcano using wooden planks, then throw the whale into the lava pool at the summit to trigger the Mutated Bowhead Whale boss fight.

What you need before you start the whale sequence

Both whale fights run back to back, so everything you carry in has to last across both. There is no chance to restock once the final boss is live. Prepare for the pair as one long encounter rather than two separate ones.

Item	Why you need it
Scientific Lure	Catches the five Volcano fish the scientist asks for. Costs $500.
Fish Bucket	Bait that summons the Bowhead Whale. Given by the hazmat scientist after five fish.
Fully upgraded Assault Rifle	Main damage source for both whales. Buy every attachment and bullet upgrade you can.
Lava-cooked fish	Healing for both fights. The lava cooks fish at 1.5x value with no timing window.
Dynamite	Blows up four or five fish at once, the fastest way to build a food pile and gather the bait fish.

Throw dynamite into the water and scoop up everything it kills, then cook the whole pile in the lava flows around the military camp. Fill your inventory with cooked fish and drop spare piles on the ground near the base so you have healing waiting for both phases. Carry far more than feels necessary.

Hotbar slot six selected on a fish item with an inspect F prompt on the volcano terrain — Selecting a caught fish in the hotbar before cooking it in the lava for healing. Image credit: Dazed Games / via @PazarGamingGuides

Summon and kill the Bowhead Whale

Catch five fish native to Volcano island with the Scientific Lure and hand them to the scientist in the yellow hazmat suit. He gives you the Fish Bucket in return.

Equip the Fish Bucket as bait and reel in the Bowhead Whale. This starts the first whale fight. You can hook the whale on other islands too, such as the bird island, where buildings and cover make the fight easier.

The Bowhead Whale charges across the arena and launches high into the air to slam down on your position. Run out from under it the moment it shoots skyward, then pour rifle fire into it between attacks and eat a cooked fish right after any hit lands.

Once the whale is down, pick up the carcass and store it in your inventory. Keep it. Do not sell it, because the body is the trigger for the final boss.

Note: If you drag the whale far from where it spawned, it can despawn. There is a range at which it disappears, so if you sail ahead of it, let it catch up rather than racing off.

Throw the whale into the volcano

Use the wooden planks to build a path up the steep, rocky slope to the rim of the volcano. Watch the active lava streams on the way up, since touching them deals damage. Careful parkour is what keeps your health intact for the fight ahead.

At the summit you reach a large open pool of lava in the crater. Equip the whale carcass and throw it directly into the lava.

Player aiming at a glowing lava-filled crater at the volcano summit with an inspect prompt on screen — The open lava pool at the summit where the whale carcass is thrown to spawn the final boss. Image credit: Dazed Games / via @PazarGamingGuides

Throwing the whale into the crater immediately spawns the Mutated Bowhead Whale. Drop back down to the supplies you stashed near the military base, because the final boss is now active and there is no gap to prepare.

Beat the Mutated Bowhead Whale

The lava whale is bigger, tougher, and hits hard enough to kill you in a couple of strikes. It also spits burning lava from its body. This is the one genuinely difficult fight in the game, and it is won on movement and healing rather than any trick.

Attack	How to react
Roll	Hold your distance and strafe around it.
Stomp	Move out from under it the instant it winds up.
Lava pools	Watch the floor and dodge the pools as carefully as the boss.
Lava meteorites	Keep moving across the arena so the shots miss.
Phase 2 sky launch	Reposition as it rises, then avoid the stomp it lands with.

Open with the fully attached Assault Rifle and eat a cooked fish every single time you take damage rather than waiting until you are low. Phase 2 is where runs end. The boss becomes far more aggressive, stomps almost constantly, and periodically leaps into the sky to rain attacks down, so never stand still.

Mutated Bowhead Whale boss health bar visible while a rifle fires during the final fight — Firing the maxed assault rifle at the Mutated Bowhead Whale during the final boss fight. Image credit: Dazed Games / via @PazarGamingGuides

Tip: Some players cheese the fight solo by fishing the whale up on the bird island and peeking from inside the armoury shack, where the whale cannot reach you while it is airborne. In co-op the fight is much more manageable. One player holds the boss’s attention while another works a firing line, and reviving each other means a single mistake no longer loses the run. The army tent on the volcano also makes good cover.

Finish the game after the kill

Killing the Mutated Bowhead Whale drops a Whale Fin. That is not the ending on its own. You need to hand the fin in to roll the credits.

Pick up the Whale Fin the boss leaves behind.

Carry it back to the hazmat scientist and trade it in. He hands over the keys to the military boat, the RHIB.

Board the RHIB and start it. The boat takes you to the mainland and plays the game’s ending and credits.

You know the sequence worked when the Mutated Bowhead Whale spawns from the crater after the throw, when the Whale Fin appears on death, and when starting the RHIB rolls the credits. The most common reason the final boss never appears is throwing an unbeaten whale or losing the carcass, so make sure you kill the regular whale first and keep its body in your inventory before you climb.

Finishing the game does not wipe your progress. You can continue on the same save with every purchase and weapon upgrade intact, which is the moment to complete your creature collection and spin the roulette for new weapon skins.