Drive to Mahabalipuram, whose Shore Temple has majestically stood on the beach since 7th century. Admire also other monuments like Arjuna's Penance, an epic recreated on stone, or the five seachore Rathas.
Reach Pondicherry and wander in its beautiful boulevards and gothic structures (Sacred Heart Church) inherited from brief French occupation. Also visit Auroville (city of dawn), the famous center for spiritual learning and meditation named after Guru Sri Aurobindo Ghosh.
Board a Kettuvalom, a traditional rice boat made from bamboo and converted into a luxurious houseboat on sail through coconut lagoons and narrow canals of Kerala Backwaters. Leisurely relax until you reach Kumarakom the next day.
Different communities (Jewish, Muslim, Chinese, Portuguese, Dutch…) have long cohabited in Kochi (ex-"Cochin"), which makes it very eclectic. Walk in the narrow streets of Fort Cochin: 16th century Jewish synagogue and Catholic Church, Dutch Palace… before attending a traditional Kathakali dance show.