I've had fantastic snorkeling from both Cabo and PV. And we saw amazing whales on the snorkeling tours. Just did this 2nd week of December. I can't remember which tour operator we used for Xabo, but used Vallarta Adventures in PV. Awesome experience. Last February I also did the Riviera and we saw more whales on the PV snorkeling than on the whale watch in Cabo. I've cruised the Mexican Riviera 6 times. Enjoyed snorkeling on each cruise.