How about a trip to Japan Ryukyu Islands

Japan is not renowned for its beaches, or tropical scenery, all except Okinawa and the Ryukyu Islands. Stretched out in a long, thin chain almost down to Taiwan, these subtropical islands have a balmy warm and humid climate, far warmer than anywhere else in Japan, notably in winter, and are dotted with hills and beaches galore, all lapped by the warm waters of the East China Sea.
Your biggest “issue” here is going to be getting here. While flights from Tokyo are common, they’re prone to cancellation during typhoon season, which lasts from July to November and these islands are affected by several of them a year. If you manage to avoid these monstrous storms, which don’t always make a direct hit it must be said, then this is a truly lovely part of Japan, very unlike much of the rest of the country, with a long standing history, wonderful architecture, a distinct culture all of its own, a world-famous export in the martial art of karate, (yes, and brought to infamy in The Karate Kid back in the 80’s when they visited these very islands), and diving. They are home to some exceptional dive sites and if being underwater is your thing, this really is a place you need to make the effort to get to!