If you only went to one hot spring on Hachijojima it would have to be Miharashi no Yu. The view from the open-air bathtub is featured in just about all the guide pamphlets for the island and is really something to behold. And with the bathtub so close to the edge you can enjoy an unimpeded view of the cliffs and waves in the far distance. Unfortunately, the best views are only to be had in one of the bathing sections, but the good news is that the onsen switches the male and female baths each day. When I went it was very quiet and the lady at the reception kindly let me take pictures inside the female baths (which happened to have the side with the good view that day) while she stood guard at the entrance.