Suppose you've been to Guau-Guau Island, which is on the starting island of Isla Santuario, in the Casas Cove area, in the middle of the water. You may have seen a Mysterious Chest that is locked, and even if you explore the island, it'll be for naught as the key needed is not here.
To unlock the Mysterious Chest, you need to find the Mysterious Key obtained during a Yaran Story Fetch Quest after completing Who's A Good Boy? The Yaran story is located in Madrugada in the Costa Del Mar area. To make this story appear, you have to complete a story quest Meet the Monteros.
If you already have the key, the chest is located on the island in the picture below.
Related: All Baseball Memorabilia Locations in Far Cry 6 - Stealing Home Yaram Story
To complete the Who's a Good Boy? story fast. The pupper wants to eat Crocodile meat, so if you have some already on you, put it into the dog bowl, and story complete.
To complete Fetch Quest, all you had to do is pet Chorizo, follow him around and collect the Mysterious Key. With the Key in hand, go back to Guau-Gaua Island and unlock the chest for a F*ck Anton Rifle.
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Mark Carpenter is the Assigning Editor at Pro Game Guides. With over four years of experience in the games media, his work has graced platforms such as Metro UK and Game Rant, along with other smaller publications. He has been a devoted gamer since the Amiga days, a journey spanning roughly 31 years. When not immersed in gaming, Mark enjoys delving into the worlds of D&D, strumming his guitar, and indulging in a good read. His heart belongs to RPGs, the Final Fantasy series, and The Legend of Zelda. Moreover, he has a keen affection for dogs.