The five senses are very important in this story. Pay attention to moments when the senses are important at Camp Half-Blood or on the quest. Remember what the bonfire at the Camp Half-Blood mess hall smells like? No wonder the gods love to have food sacrificed to them. Consider how good Grover is at smelling and detecting monsters. Percy and Annabeth let their taste buds take over as they are lured into Aunty Em's warehouse, and Percy tastes his mom's chocolate chip cookies when he drinks nectar. Think about how good Grover's ears are – how he can hear the snakes hissing underneath Aunty Em's veil.
Percy is really good at noticing a million things at once. He learns to observe things like centaurs running wild in the Midwestern countryside or where the water pipes might be located in the Tunnel of Love ride. When Percy is underwater, his sense of touch is heightened, and he is able to make anything that he touches completely dry, including his clothes. Swords feel weird in his hand until he meets Riptide for the first time. Having really sharp senses seems to be a key aspect of being a hero and of Ancient Greek life. The immortal world makes the mortal world seem blah.