One more point about snorkeling. The PG supplies all the gear free and their divemasters will insure that it fits you. The quality is good. So there is no need to lug your own equipment across the Pacific.
Wendy has a custom mask to match her glasses, but uses their flippers. I use both as supplied by the ship.
You will want to take reef shoes, not so much for the snorkeling as for wading on the beaches.
You folks will have so much fun! We don't get back to the PG until December, and I'm already impatient.
-- David