I don't know what the rental gear available is like, but my general advice from living in Hawaii for a while is that if you have a nice mask that you like, you should at least bring that. It won't take up too much luggage room, and you won't have to worry about finding one that fits properly from the rental place.
Radiance of the Seas to Alaska July 2003
First cruise-10th anniversary
We just came back from a cruise on the "Majesty of the Seas" We went snorkeling at Cococay and my husband had his own mask & snorkel, but they said you also need fins and an inflatable vest - so we saved $9 by taking the mask & snorkel - choice is yours.
Just returned from The Sovereign. We took our gear. I was really disapppointed with RCCL in this area. They REQUIRE you to RENT a vest for $6.00. I'm used to NCL where the vests are supplied free. It's a little thing, but it's just another thing where they nickle and dime you to death!
I always bring my own snorkel gear. We cruise quite a bit so I invested in the whole get up. I just do not like putting my mouth on something someone else has used. I know they say they clean it but I just have a very bad hang up about it.
We took our own gear on our cruise. We opted not to buy an excursion in Grand Cayman. Instead, we went to 7 mile beach and snorkeled on our own all day. We saw a stingray with her two babies, another stingray, many fish, some great coral. There was a little fish who followed us for about a half hour. He swam under my husbands chin. It was the cutest thing. We had a better time doing this than an organized tour.
take your own--a better fit & altho" on CoCo Cay they seemed to disinfect them--why take a chance? On Catalina Island, DR--the equip was not the best. Even if you just take your own mask & snorkel & rent the fins& belt you'll feel better IMHO