Blue Shark
A mini-boss fought on the same island as Pufferfish. Defeating it unlocks grilling.
How to Find It
Summoned with a Standard Boss Lure, per two independent fish-list sources.
How the Fight Works
Described in a gameplay video as weak enough to one-shot with stacked dynamite, unlike the main progression bosses.
Rewards
Per a gameplay video: bring the defeated Blue Shark to the grill NPC on the same island, and they give you a Lighter, which unlocks grilling caught creatures.
Previously held at needs-verification (only 2 of 3 guide sites mentioned it). Frame-by-frame inspection of the official release trailer settled the name: the boss health bar reads "Blue Shark" directly, across multiple consecutive frames, near the same beach shack seen in other official screenshots. It was promoted to verified on direct primary evidence rather than by majority vote of secondary sources. Its mini-boss role and the grilling unlock chain come from a single gameplay video and are not independently confirmed, so treat that specific detail as community-reported even though the boss's name itself is verified.
Related
Pufferfish
The third boss.
Grilling & Cooking
Players can grill caught creatures and eat them, including narrative/quest uses (e.g. delivering cooked food to an NPC).
Lighter
Given by the grill NPC after defeating the Blue Shark mini-boss. Unlocks grilling.
Standard Boss Lure
Boss bait for the Blue Shark mini-boss on Island 3.
Island 3
The third island. Fish sell for noticeably more here, and it's home to Pufferfish and the Blue Shark mini-boss.