Gower tells us that Pericles and Thaisa have been married and now she's knocked up. A dumb show reveals Pericles receiving a letter, then he, Thaisa, and their nurse taking leave of Simonides. Gower explains that Antiochus and his daughter are reported dead and Helicanus has refused the crown of Tyre. Pericles, the pregnant Thaisa, and Lychorida the nurse set sail but encounter a sea storm.
Pericles onboard prays for the tempest at sea to wane. The violent storm has sent Thaisa into labor, and the nurse emerges with an infant, saying Thaisa has died giving birth: "Here's all that is left living of your queen: / A little daughter" (III.i.20-21). Pericles has found a Shakespearean eloquence in this scene and expounds on the circumstances.
The sailors' superstitiousness demands that Thaisa's corpse be chucked overboard, so Pericles orders a coffin to be made. The sailors have a chest, "caulk'd and bitum'd ready" (III.i.71). So "He is obliged to cast her overboard" (Ogburn and Ogburn 129). Pericles decides to head for Tharsus where Cleon can serve as a foster parent for the infant who, says Pericles, "Cannot hold out to Tyrus" (III.i.79).
Thaisa has been given the heave-ho near Ephesus, where the admirable Lord Cerimon studies medicine:
'Tis known, I everHis name probably comes from the Latin cærimonia = the sacred, the divine (Clark 72), and he has been seen as a representation of Elizabeth's trusted astronomer Dr. Dee, with whom Oxford probably studied (Clark 71; Ogburn and Ogburn 129; cf. Sonnet 14).
But a gentleman asserts that he has won honors throughout the realm through all he's cured.
Servants bring in a chest that the sea tossed ashore. When they wrench it open it yields "A delicate odor" (III.ii.61), and of course this turns out to be Thaisa's coffin, containing her body, bags of spices, and a note requesting her to be buried in a manner befitting a queen and daughter of a king. Cerimon thinks she's not dead yet: "Death may usurp on nature many hours, / And yet the fire of life kindle again / The o'erpress'd spirits" (III.ii.82-84). With the help of some music, indeed Thaisa wakes up, disoriented: "O dear Diana, / Where am I? Where's my lord? What world is this?" (III.ii.104-105). "Is this not strange?" asks a gentleman. "Most rare," says another (III.ii.106). "Saint Paul wrote of the Ephesians that they 'used curious arts' (Acts of the Apostles 19:19), or magic, so Shakespeare's audience would not have been surprised to find at Ephesus just such a natural magician, the doctor Cerimon" (Garber 768).
So, "Pericles marries Thaisa, they have a daughter, and then he is quickly separated from both. In real life, de Vere married Anne Cecil, she bore him a daughter (Elizabeth Vere), and then they were separated -- but at his own instigation" (Farina 100).
Pericles has spent about a year with Cleon and his wife Dionyza in Tharsus, and now must travel home to Tyre. He has named his daughter Marina because she was born at sea, and he entrusts her to Cleon and Dionyza, "beseeching you / To give her princely training, that she may be / Manner'd as she is born" (III.iii.15-17). Pericles vows never to cut his hair (?) until Marina is married. "In the center of the play we suddenly find Pericles and Thaisa each inhabiting a wasteland: bereft of wife or husband, bereft of child. Each performs an act of self-abnegation" (Garber 770).
Mention is made of some letters and jewels that were in Thaisa's coffin. She has only partial memory, figures her husband is dead, and decides to become a vestal virgin at the temple of Diana, the goddess of chastity and of the hunt, in Ephesus. Of course, Diana of the Ephesians is a fecundity goddess, not the moon-virgin (Asimov 195).