I not heard of any hotel on Coz that has good snorkeling, but maybe the
new PLG lobby will offer improvements, assuming they impose reasonable
limits for the boat traffic.  We should all help the PLG people know
that if they keep the lobby lights off during the day, those that prefer
to snorkel at night would have more chances to enjoy that.  I'd also
like to recommend no furniture.  As far as snorkeling anywhere else on
the island, I'm afraid you're out of luck.  As a fallback option,
there's an ocean nearby that offers a pretty good second choice, and at
some beach club locales, snorkeling safely out the boat lanes is both
possible and enjoyable.

The Reef Club (an all-inclusive south of town) has decent snorkeling,
especially to the north end of the hotel's beach and up along the rocky
shore past the pier. It's not Bonaire or anything, but I saw some
interesting fish there. It's OK out front of the hotel too, but then you're
in the boat traffic...