The Grill is unlocked on the third island and can be used to cook fish and other sellable items. Cooking increases an item’s selling price while also making fish more useful for recovering health and hunger during boss fights.

The Grill is unlocked on the third island and can be used to cook fish and other sellable items. Cooking increases an item’s selling price while also making fish more useful for recovering health and hunger during boss fights.

Find the Grill master standing beside the unlit Grill on the third island and speak to him. He will ask you to bring him a Blue Shark.
Purchase the Standard Boss Lure for $280 from the island’s shop. Make sure you buy the boss version, as the cheaper pink Standard Lure is used for catching regular fish.

Equip the Standard Boss Lure on your fishing rod and cast it into the water to summon the Blue Shark. Move sideways when it begins spinning towards you and attack it from a safe distance.

After defeating the Blue Shark, carry it back to the Grill master. Completing his request gives you access to the Grill and unlocks the Grill master achievement.
Hold or place your catch over the Grill’s flames. Use the Inspect button, which is F by default, to view the item’s cooking multiplier while it heats up.
The multiplier will gradually increase from its original value. Remove the item from the Grill as soon as it reaches 1.5x, as this is the highest cooking bonus available.
You do not need to flip the fish or complete another minigame. Simply watch the multiplier and remove it at the correct time.

A properly cooked item can be sold for 1.5 times its normal price. Cooking valuable catches before selling them is therefore a useful way to earn additional money for weapons, lures and boat upgrades.
Cooked fish can also restore health and hunger when eaten. Keep several cooked catches in your inventory before difficult encounters such as the Pufferfish fight instead of selling everything.
The Grill also works on weapons and other sellable items. Cooking a weapon increases its selling price but does not improve its damage or other combat stats, so only cook equipment you intend to sell.

Leaving an item over the flames after reaching 1.5x will eventually burn it. A burnt item turns black, loses its selling value and provides very little health or hunger when eaten.
Burning is normally a waste, but eating a burnt creature unlocks the Yummy in My Tummy achievement. Use a cheap catch if you want the achievement rather than sacrificing something valuable.
