God of the seas and any big body of water. Well water is plentiful on Teolin, so you can imagine this is a rather powerful god on this world.
Any person sailing the seventeen seas (or more) of Teolin usually reveres Poseidon, even if they follow another deity, they still want to appease this frightful guardian of the seas, rivers and lakes.
Poseidon is the protector of all large body's of water and the creatures that dwell in those waters. He is known for not being light on those who he feels trespass on his grounds.
Since earthquakes and large body's of water form formidable weapons in the form of tidal waves, so many a coastal city tries to keep Poseidon appeased.
Most of the temples of Poseidon are located close to sea. Those that are not, are located close to larger lakes.
All temples are located overhanging the body of water or have a private pier overhanging the body of water they are located next to. This pier or the part of the temple overhanging the water is typically used to give offerings to Poseidon. These offerings are given often and plentiful as Poseidon is known to be an easy to anger god. Attending services
Clerics of Poseidon are among the ones to travel very much. Often they travel with ships, to protect the ships from harms way. Any diplomat traveling by ship will always make sure that he is accompanied by at least one Cleric of Poseidon.
Fortunately for Clerics of Poseidon, his services do not need to be performed in temples, as they have many a service to perform. For their prayers to be answered, the only thing they have to do, is lead one service for every level per ten weeks.
Besides the service requirement, Poseidon does not care about any thing else.
Any other divine magic users that follow Poseidon are aquatic creatures.