Poseidon

  Poseidon was the brother of Zeus and the god of the sea. He is often shown carrying a trident, a three-pronged weapon like a big fork (in the statue left it's gone missing).
  With his trident Poseidon could stir up the seas, creating storms and waves. He was also known as the earth-shaker, for he caused earthquakes.

Poseidon and Odysseus

Poseidon was furious when Odysseus blinded the Cyclops, for he was Poseidon's son. After that Odysseus was blown about the seas, shipwrecked, and lost all his men.

   Poseidon was often shown steering a chariot drawn by dolphins. His palace was deep under the sea.

Worship of Poseidon

Poseidon was worshipped especially by sailors to make sure they had safe journeys. The Trojan war was won when the Greeks pretended to leave a wooden horse to Poseidon (the horse was his animal) to bless their journey home. The Trojans took it into the city, not realising Greek soldiers were hidden inside.
  Temples

There were temples to Poseidon all over Greece, including the one above at Sounion, on the coast near Athens.