Boss Fights & Island Progression
Islands unlock sequentially: defeat the boss guarding your current island to progress to the next, more dangerous one.
Seven bosses are now on record (one still disputed by name), five read directly off in-game HUD text in the official trailers (see the linked boss pages). Specific island names are still unconfirmed, though the island count and general order are reasonably corroborated. Official trailer footage confirms: you can't respawn during a boss fight, but teammates can revive you. A gameplay video adds detail on how boss fights actually work: bosses are summoned with a specific quest item (e.g. an Empty Beer Can for the first boss), and each boss has a secondary bar below its health bar that must fully deplete before attacks land. Hitting the boss before that bar is "done" reportedly does nothing.
Related
Spidercrab
The first boss, guarding the starting island.
Giant Piranha
The second boss, unlocked after clearing Spidercrab.
Pufferfish
The third boss.
Blue Shark
A mini-boss fought on the same island as Pufferfish. Defeating it unlocks grilling.
Mutated Bowhead Whale
The final boss. Named identically across every source checked, and the fight itself is independently confirmed by an official Steam achievement.
The Old Pike
A named boss-style encounter: a large pike fish with its own health bar labeled "The Old Pike."
Albatross
The Island 4 boss: a bird-type creature summoned by placing a caught Tuna on the ground as bait. Its exact name is disputed across sources.