His mortal sons were Theseus, Pelias, Neleus and Hippothoon.
Amymone's son by Poseidon was called Nauplius.
He was the son of Poseidon and a mortal woman.
going back to the mortal world to visit his son when fobiden
Yes, mortal men and women can worship Poseidon.
In Greek myth, Perseus is the son of Zeus and Danaë. In the modern "Percy Jackson" series by Rick Riordan; Perseus "Percy" Jackson, is the son of Poseidon and Sally Jackson.
Yes, Achilles was the son of Peleus (mortal) and Thetis (divine). (Hercules) Heracles was the son of Zeus (divine) and Alcmene (human).
To be a god.
Thetis gave prophesy that she would have a son greater than his father; Zeus and Poseidon did not pursue her afterwards but made it so she would have a son by a mortal. That son was Achilles.
A demigod is half mortal and half god, meaning one parent is god and one parent is mortal. a demigod of Poseidon is a demigod with Poseidon as his/her father and a mortal mother. an example of this is Percy Jackson in the "Percy Jackson and the Olympians Series" By Rick Riordan
Yes, Triton is the son of Poseidon.
A Cyclops son of Poseidon was Polyphemus.
Any son of Poseidon and a mortal woman is a demigod, as Polyphemus, Orion and Theseus. They did not belong to the sea. God of the sea - yes. Demigod of the sea - no.