The bahamas, in particular Bimini, are good for great hammerheads in January - March.
If you go to Cocos, I recommend any of the boats in the Undersea Hunter group. They are top notch and the diving is done from steel pangas. These are much more stable than inflatable zodiacs that other boats use. I can't imagine riding out to Alcyone at Cocos in an inflatable over all those waves. And getting out of the water... no thanks
- pndldy likes this