The Trident of Poseidon is the signature weapon of Poseidon, the god of the sea. It is a three pronged spear with thick energy bolts surging through it. To regular mortals, it appears as a surfboard, fishing rod, or ice cream, when he is by the beach due to the Mist. There is an attachment for Poseidon's trident on his throne, where one would expect a fishing pole on a mortal fisherman's chair.
Poseidon wields his trident on a number of occasions. During the contest with Athena over the possession of Attica, Poseidon strikes the Acropolis with the trident to produce a well of seawater. In a similar myth Poseidon strikes the ground with trident to produce a horse for mankind, while his rival Athena produces an olive tree. The oldest coins of Poseidonia from the 6th century BC depict trident wielded by Poseidon in his right hand, similar to Zeus's thunderbolt.
In another myth, Poseidon creates a spring or springs with the strike of his trident to reward Amymone for her encounter with him. In a version of another myth Poseidon wields his trident to scare off a satyr who tries to rape Amymone after she mistakenly hits him with a hunting spear. There is also a myth where Poseidon touches the island of Delos with his trident, affixing it firmly to the sea floor
Through the trident, Poseidon has the ability to control the ocean, making tsunamis and waves, shake the earth, and shatter any object. It can also project massive beams of blue lightning that can transform targets or even outright destroy what it hits. It is shown that when he hits a sea monster, it transforms into a goldfish. The trident is shown to be powerful enough to instantly destroy a giant squid, which was "larger than any skyscraper", dissolving it like "food coloring".
It is also said that earthquakes are caused when Poseidon strikes his trident into the ground. That is why Poseidon is called "The Earthshaker". Furthermore, since he also uses his Trident to call up sea storms, Poseidon is also referred to as "The Stormbringer." The Trident was also one of the few godly weapons to significantly injure Typhon himself during the Olympians' final battle with him.