Just came back from 2 weeks in Kerala and Tamil Nadu. We finished our trip by 3 days in Kovalam.
While the beach is nice (soft white sand, clear water but high waves), It is not at all the St-Tropez or Miami of Miami. More like a beach station stuck in the 80's.


Try "TIDES" seafood restaurant inside the Leela Kovalam hotel.
Link below:
https://www.theleela.com/en_us/hotel...ing/the-tides/


Regarding the 'backwater boat ride', we did a half-day ride during the day. We found the ride very boring. Just my $0.02, perhaps there's more to see if you spend the night on the boat.
Bring plenty of books