You could redeem for Carnival or Royal Caribbean gift cards if you happen to use either of those lines. The Carnival card appears not to be valid on the other brands owned by Carnival Corporation:
https://rewards.thankyou.com/b2r/mer...vel-gift-cards
The points are worth $0.01 when redeemed for such cards. I would expect that rate or lower when using points to purchase a cruise.
Thanks Mia. I've cruised with Carnival, Royal Caribbean, and Norwegian. All three offer roughly the same product. So The former two are fine.