Neptune's Trident is treasure that can be obtained in the game Sly Cooper: Age of Thieves in the episode Coopers of the Caribbean. It is worth 234 coins and the allotted time needed to get to the safehouse is twenty-two seconds.
"For the longest time, Neptune's Trident had lay dormant in the ocean depths. But thanks to Henriette and her crew, it is now one of their greatest finds. It was also their first, making this nostalgic treasure a truly important part of history."
It is located near a cave behind the Emerald Eclipse, passed two palm trees guarded by flashlight guards. Sly needs the Mummy Costume to reach it.