Brackish Blunder [The Lost Caverns of Ixalan]

Cost: 1 U Return target creature to its owner's hand. If it was tapped, create a Map token. (It's an artifact with " 1 , T , Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.") When the Malamet told him to avoid the river, he thought they meant it wasn't safe to drink.