Tokyo's Tropical islands
Tokyo's outer islands are very diverse. Most of them are volcanic and some of them are quite far from the main part of Tokyo. Most of the main islands are accessible from Takeshiba Pier, where you can find Tokyo's main ferry terminal. Many of the main islands are also accessible by plane, from Chofu Airport.
The main island closest to Takeshiba is Oshima. The large ferry from Takeshiba takes 8 hours to get to Oshima. A smaller and speedy boat takes 1 hour and 45 minutes to get there. However, Oshima is actually much closer to Kanagawa and Shizuoka, which are to the west and southwest of Tokyo. The high speed boat from Atami in Shizuoka takes only 45 minutes to Oshima.
From Oshima, the larger ferry keeps traveling south to the outer islands. Niijima, my favorite (so far), is a little over 10 and a half hours from Takeshiba. Niijima is very popular among surfers, for the curling waves and white sand beaches. I was there on August 31, 1997 in a van with a group of friends when we heard the news of Princess Diana's death on the car radio.
Shikinejima and Kozushima follow Niijima. Both islands are also quite popular among scuba divers and others. But Miyakejima, Mikurajima, and, especially, the larger Hachijojima are even further south and much more tropical. These islands are often compared with Okinawa for their lush island growth and rustic resort facilities.
Finally, the last group of islands are part of the Ogasawara Islands, which were designated a World heritage site by UNESCO in 2011. Although there are 30 islands in the cluster, Aogashima, Chichijima, and Hahajima are the only ones directly accessible from Tokyo. Chichijima is accessed from Takeshiba by ferry, taking 25 hours and 30 minutes!
You can find out more on the Tokyo Islands here: