Definition: The Isthmian Games were one of four sets of panhellenic games. Held to honor the god Poseidon, the home of the Isthmian Games was the Sanctuary of Poseidon in Corinth. Pindar describes the games as having been started as funeral games for Melikertes-Palaimon [see Melikertes-Palaimon, Hero of the Isthmian Games], grandson of Cadmus of Thebes. The Athenians attributed the founding to Theseus, in honor of his defeat of the pine-bender Sinis.
The prize at the Isthmian Games was a wild celery or pine crown*.
The isthmus in the name of the games lies between the Saronic and Corinthian Gulfs. It is what made Corinth such a commercially important Greek city.
The Isthmian Games were established in 582 B.C. [Neil Asher Silberman, John K. Papadopoulos, Ian Morris, H. A. Shapiro, Mark D. Stansbury-O'Donnell, Frank Holt, Timothy E. Gregory "Greece" The Oxford Companion to Archaeology. Brian M. Fagan, ed., Oxford University Press 1996.]
*"The Isthmian Victory Crown," by Oscar Broneer. American Journal of Archaeology, Vol. 66, No. 3. (Jul., 1962), pp. 259-263.
Examples: The Isthmian Games were held the second and fourth years of each Olympiad.