Okinawa (Ishigaki) in october?

Question:

Hi guys
Me and my wife are planning honey moon in Okinawa. We would like to go around 20/25thof October to Kabira, Ishigaki.
Our concern in the weather condition specially sea. We’ve been warned in travel agency that sea might be cold and presence of jellyfish can be a big problem.
However, I read somewhere that till December water in sea in warm. We are confused now and don’t know what to do.
Regards
Mario

Answer:

Maybe you can swim. But it might be a liitle cold.
As you know, you can swim in Kabira bay, because of strong current.

http://www.japan-guide.com/e/e7201.html