How to Fish: Mutated Whale slams and lava attacks

How to fight the Mutated Bowhead Whale

Keep shooting while staying clear of the Mutated Bowhead Whale's body, landing point and lava pools. Watch its descent before committing to another shot. After half health, expect chained jumps rather than assuming the first landing ends the attack.

It has 38,000 HP on Default difficulty with one player and a five-minute timer. Prepare before starting the volcano encounter. Island 5 sells the Assault Rifle for 20,000, Sniper Rifle for 3,800 and SMG for 650. These are available choices, not a required purchase list or a tested damage ranking.

How to start the volcano encounter

Use the Fish Bucket to catch the ordinary Bowhead Whale. Defeat it, then release its body into the volcano trigger while no other boss is active. The eruption summons the mutated whale.

The ordinary whale and mutated boss are separate encounters. The Scientist's whale walkthrough explains the full sequence and the final hand-in.

Move away from the landing point

The whale can rise into the air and track its target during the descent. Its landing creates an explosion, so moving away from the body alone may not clear the blast. Watch where it is coming down and keep moving out of that area.

Do not rely on a high ledge to stop this attack. The whale can deliberately jump when its target is above it.

The second phase can chain three jumps. Although the whale has a landing cooldown, another jump in the chain can begin immediately. There is no guaranteed 1.5-second stationary opening after every slam. Wait until the sequence has actually ended before moving closer.

Avoid fresh lava pools

The whale fires lava projectiles, normally in groups of four. Their pools remain for about 20 seconds and apply a burning status when touched. Move toward clear ground instead of repeatedly retreating through the same landing area.

Body contact is also dangerous and can apply fire. A clear patch beside the whale is not permission to stand against it while reloading.

What changes at half health?

At half health, the whale briefly becomes invulnerable and begins a larger lava barrage. The transition animation lasts about three seconds, but the sequence of lava shots can continue beyond it.

Use the invulnerable interval to create room or reload while continuing to avoid the boss and existing pools. Resume firing when the health bar can fall again. Do not treat the transition as a harmless pause or rush underneath the whale as soon as the animation ends.

Why its health rises in co-op

Each additional connected player adds 50% of its difficulty-adjusted base HP. Joining during the encounter can increase both its maximum and current health. Leaving does not remove that increase. Assemble the group and prepare equipment before starting the volcano trigger.

Take the Whale Fin back

Collect the Whale Fin after the boss dies. Return it to the Scientist and take his offered keys. The final boat walkthrough covers the remaining actions needed to leave.