The Manta is the 1.1.0 mini-boss. It needs no bait: push the loose black barrel on the Manta mini island into the sea and it comes out of the water. It is optional, it pays in euros, and it counts as a Fishipedia entry for Collector.

Find the barrel islet

Mini islands appear at random once you sail away from the main islands. The one you want is two small rocks joined by a wooden bridge, with a stack of copper barrels and a round sign warning you not to throw barrels into the sea. The black barrel stands near the stack.

The Manta mini island's wooden deck with a dark barrel in the foreground, a pile of copper barrels and a round no-throwing sign

Summon it

Pick up or push the black barrel and drop it into the water. It has to sink about 1.5 m under the surface before it turns into the Manta, so throw it off a spot where the water is deep enough rather than into the shallows.

If nothing happens, check two things. Another boss may still be out, in which case the barrel does nothing until that fight ends. And each islet gives you one barrel per visit, so a barrel already used means you need a new islet.

Gear

A fully upgraded Assault Rifle is the reliable choice, with a few sticks of Dynamite for burst damage when it lands near you. The Manta has 8,400 health on Normal (75% on Easy, 125% on Hard), so a weaker gun turns this into a long fight. The Bow works for players who want a challenge.

Fight it on solid ground

The Manta is fast and erratic: it jumps around rapidly and launches itself out of the water to hit you. On the tiny islet there is almost nowhere to dodge, and players who stay there tend to get killed quickly. Standing under the bridge when it goes up can save you, but the better plan is to move the fight.

Fighting on the wooden bridge of the islet with an Assault Rifle while the Manta health bar shows about a quarter of its health gone

The Manta spawns wherever the barrel goes into the sea; it is not tied to the islet. Carry the barrel on your boat to a large island, such as the Volcano, and drop it into the water there. Before you do, throw Dynamite into the water to collect a few fish to eat. You get room to move and the boss still appears.

Keep steady fire on it while it moves, and add Dynamite when it lands. The white escape bar under its health bar still applies.

If you lose

A failed attempt uses up the barrel. Sail away until the islet despawns, then find a new Manta islet; it comes with a fresh barrel.

Some videos show players editing their save file to fill the inventory with barrels. That is outside normal play and can damage a save, so this guide does not cover it.

What it pays

The dead Manta weighs about 500 kg and sells for euros, not dollars. Its base value is €60, and players typically see €79 to €99 raw because size and kill bonuses raise the price. Cooking it on a grill or in lava multiplies that by up to 1.5; one cooked Manta sold for €185. Any NPC will buy it, and one kill covers the €25 Bow with plenty left over for its upgrades.