Dead Island Walkthrough Part 6: Act 1 - Resort - Ch. 2 - A Piece of Cake

You receive the "A Piece of Cake" quest from Sinamoi after finishing "To Kill Time". This quest is part of the main storyline.

Sinamoi (in the lifeguard tower) wants you to bring him 3 cans of food.

He suggests you look for those cans in the bars near the swimming pool. But the cans can be found in other places too. You might have already looted them- check your inventory to see if you already have three, and if you do, just turn them over to Sinamoi to complete the quest. Otherwise, go looking for them.

You can follow Sinamoi's advice and head to the swimming pool area, or just drive around in the truck with the quest active, and seek the red hand icons which will lead you to the cans of food. Whichever way you choose, there will always be zombies guarding the cans, so  stay on guard and be ready to fight whatever comes your way.

Once you have collected 3 of them, get back to Sinamoi at the lifeguard station and hand them in to complete the quest.  He will complain about the amount of food and send you on the  next quest, Seek N Loot, to search for some more food.