If you could only go to Cocos once in your life what 1 or 2 months would you go? The highest probability of having awesome diving is what I am looking for.
I've now been in May-June (2010) and March (2011) and while both trips had good weather and minimal rain, there were definitely more hammerheads there in March. I have heard that the peak season for the hammers is September, but that also tends to be a time of rainier weather. This page will give you an idea of what to expect weather-wise, but remember, it's a rare trip when you see no rain whatsoever: http://underseahunte...05/climate.html Also, if you look back at various trip reports here, they tell you what the weather & water conditions were like on each trip: http://underseahunte...ripreports.html Personally, I would go any time of the year but if I had my choice I would like to see what September is like.
I keep reading about how El Nino years are not good years to go to Cocos. How do you find out what years are El nino are in effect for cocos? and how far in advance do they know?
El Niño year are not good because the warmer waters tend to keep the hammerheads to depths beyond recreational scuba. But they may also bring in different creatures. You may notice coral bleaching during or after an El Niño but coral isn't the reason one goes to Cocos. This page will tell you a bit more about El Niño in general: http://www.elnino.noaa.gov/
By the way, if you haven't yet booked a boat I would highly recommend the Undersea Hunter boats. They and their crew are clean, professional, safe, wonderful, and the best group to dive Cocos with.
-Gina
