Okinawa October suggestions

Hello!
I will be in Hong Kong in October with my husband and I am planning a trip to Okinawa, probably around 7 days, ideally from October 7th to October 14th.

Some key points:
– we really don’t want to rent a car, but rely on public transportation or an occasional taxi instead. We would probably also book some activities with transportation included;

– we want to see the aquarium as seeing whale sharks is at the top of my husband’s bucket list;

– we plan to do some sightseeing, but mostly a lot of snorkeling and possibly some hiking

Do you think splitting 7 nights between Naha and one of the Kerama islands is a good plan?

Zamami and Tokashiki seem amazing; a few years ago we went to Miyajima and stayed the night, and we loved the vibe when the day trippers were gone; small island, a few restaurants, walkable etc… do they have a similar vibe, yet tropical?

I was considering also Ishigaki or Miyako but I am afraid one needs a car to visit those. Is the snorkeling in the Keramas comparable to those two?

Thanks a lot in advance!!

by Gabe4Pay