Just got back from Key West. Stayed at the Doubletree.
Scuba off Key West was good -- not terrific, but good. We went to a few reefs through Subtropic, arranged by the Conceirge staff at the Doubletree. The crew on the boat were friendly & helpful arranging gear, walking through the routine, etc.
We were on shallow dives, ~30', because my girlfriend just got certified herself. For someone just certified, you may want to keep it reasonable shallow.
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On the road, In the air,
I enjoy travel, From here to there.