For 10 points, name this Greco-Roman god of the oceans.
This god was the dedicatee of the Isthmian Games. He slept with Aethra on the same night as Aegeus, and ordered the death of Hippolytus at the request of his son Theseus. This god lost a contest when his offering was judged inferior to the olive trees of Athena. His offspring include the shape-shifter Proteus and the god Triton. This god of earthquakes was the brother of Zeus and was often depicted with a trident. For 10 points, name this Greco-Roman god of the oceans.
This god was the dedicatee of the Isthmian Games. He slept with Aethra on the same night as Aegeus, and ordered the death of Hippolytus at the request of his son Theseus.
{Poseidon} [or {Neptune}]