The world of Tlalak (and its natives the Tlalakans) was named after Tlaloc, the Aztec god of rain and water who ruled Tlalocan the "heaven" in Aztec mythology reserved for those who died by a water-related death (drowning, choking, etc). One of the Tlalakans even has the name of Tlaloc.
One of the Tlalakan natives is named Chac, after Chaac the Mayan god of rain.
The term "sea change" (used for the episode title) simply means a significant transformation. However, it was coined by William Shakespeare to refer to the substance of a body literally being changed by the sea; a similar event that occurs in the episode to many characters, notably Seaspray, Alana and Rumble.