I'm heading to TDR in May, and am going to do a side trip to see an aquarium--mainly to view the whale sharks. I hear that Yokohama has a really good aquarium and that was where I had planned to go, since it's just a train ride from TDR, but that Okinawa has an awesome one (but far and expensive to get to from Tokyo). While I'm researching travel options, anyone ever been to either and can give any recommendations? I've already ruled out Osaka and Toba aquariums. I'm looking to only make this side trip a one or two day (counting travel). Thanks.